User Equipment (UE) and Methods for Vehicle-to-Vehicle (V2V) Sidelink Communication in Accordance with a Short Transmission Time Interval (TTI)

ABSTRACT

Embodiments of a User Equipment (UE) and methods for communication are generally described herein. The UE may select, from a plurality of short transmission time intervals (TTIs), a short TTI for a vehicle-to-vehicle (V2V) sidelink transmission by the UE. The short TTIs may occur within a legacy TTI. The short TTIs may be allocated for V2V sidelink transmissions by non-legacy UEs. The legacy TTI may be allocated for V2V sidelink transmissions by legacy UEs. The UE may transmit, in accordance with the legacy TTI, a legacy physical sidelink control channel (PSCCH) to indicate, to legacy UEs, the V2V sidelink transmission by the UE. The UE may transmit, in accordance with the selected short TTI, a short PSCCH (sPSCCH) to indicate, to non-legacy UEs, the V2V sidelink transmission by the UE.

PRIORITY CLAIM

This application claims priority to United States Provisional PatentApplication Ser. No. 62,475,690, filed Mar. 23, 2017, and to UnitedStates Provisional Patent Application Ser. No. 62,476,147, filed Mar.24, 2017, both of which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

Embodiments pertain to wireless communications. Some embodiments relateto wireless networks including 3GPP (Third Generation PartnershipProject) networks, 3GPP LTE (Long Term Evolution) networks, and 3GPPLTE-A (LTE Advanced) networks. Some embodiments relate to FifthGeneration (5G) networks. Some embodiments relate to New Radio (NR)networks. Some embodiments relate to sidelink communication. Someembodiments relate to vehicle-to-vehicle (V2V) communication. Someembodiments relate to transmission of signals in accordance withdifferent transmission time intervals (TTIs), including but not limitedto short TTIs and legacy TTIs.

BACKGROUND

Mobile devices may exchange data in accordance with sidelinkcommunication. In some cases, such as when mobile devices are out ofnetwork coverage, the mobile devices may perform sidelink communicationautonomously with limited or no assistance from a base station. Varioususe cases for sidelink communication are possible. In an examplescenario, sidelink communication in accordance with a low latency may beused, which may be challenging. There is a general need for methods andsystems to enable sidelink communication in these and other scenarios.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a functional diagram of an example network in accordance withsome embodiments;

FIG. 1B is a functional diagram of another example network in accordancewith some embodiments;

FIG. 2 illustrates a block diagram of an example machine in accordancewith some embodiments;

FIG. 3 illustrates a user device in accordance with some aspects;

FIG. 4 illustrates a base station in accordance with some aspects;

FIG. 5 illustrates an exemplary communication circuitry according tosome aspects;

FIG. 6 illustrates an example of a radio frame structure in accordancewith some embodiments;

FIG. 7A and FIG. 7B illustrate example frequency resources in accordancewith some embodiments;

FIG. R illustrates the operation of a method of communication inaccordance with some embodiments;

FIG. 9 illustrates example multiplexing arrangements that may be used inaccordance with some embodiments;

FIG. 10 illustrates example multiplexing arrangements that may be usedin accordance with some embodiments;

FIG. 1I illustrates example multiplexing arrangements that may be usedin accordance with some embodiments;

FIG. 12 illustrates example arrangements that may be used in accordancewith various transmission time intervals (TTIs) in accordance with someembodiments;

FIG. 13 illustrates example arrangements that may be used in accordancewith various TTIs in accordance with some embodiments;

FIG. 14 illustrates example arrangements that may be used in accordancewith various TTIs in accordance with some embodiments;

FIG. 15 illustrates example arrangements that may be used in accordancewith various TTIs in accordance with some embodiments;

FIG. 16 illustrates example arrangements that may be used in accordancewith various TTIs in accordance with some embodiments;

FIG. 17 illustrates example arrangements that may be used in accordancewith various TTIs in accordance with some embodiments;

FIGS. 18A-B illustrates example resource assignments that may be used inaccordance with some embodiments;

FIG. 19 illustrates example resource assignments that may be used inaccordance with some embodiments;

FIG. 20 illustrates example techniques for resource selection inaccordance with some embodiments;

FIG. 21 illustrates example techniques for resource selection inaccordance with some embodiments;

FIG. 22 illustrates example techniques for resource selection inaccordance with some embodiments; and

FIG. 23 illustrates example techniques for resource selection inaccordance with some embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1A is a functional diagram of an example network in accordance withsome embodiments. FIG. 1B is a functional diagram of another examplenetwork in accordance with some embodiments. In references herein. “FIG.1 ” may include FIG. 1A and FIG. 1B. In some embodiments, the network100 may be a Third Generation Partnership Project (3GPP) network. Insome embodiments, the network 150 may be a 3GPP network. In anon-limiting example, the network 150 may be a new radio (NR) network.It should be noted that embodiments are not limited to usage of 3GPPnetworks, however, as other networks may be used in some embodiments. Asan example, a Fifth Generation (5G) network may be used in some cases.As another example, a New Radio (NR) network may be used n some cases.As another example, a wireless local area network (WLAN) may be used insome cases. Embodiments are not limited to these example networks,however, as other networks may be used in some embodiments. In someembodiments, a network may include one or more components shown in FIG.1A. Some embodiments may not necessarily include all components shown inFIG. 1A. and some embodiments may include additional components notshown in FIG. 1A. In some embodiments, a network may include one or morecomponents shown in FIG. 1B. Some embodiments may not necessarilyinclude all components shown in FIG. 1B, and some embodiments mayinclude additional components not shown in FIG. 1B. In some embodiments,a network may include one or more components shown in FIG. 1A and one ormore components shown in FIG. 1B. In some embodiments, a network mayinclude one or more components shown in FIG. 1A, one or more componentsshown in FIG. 1B and one or more additional components.

The network 100 may comprise a radio access network (RAN) 101 and thecore network 120 (e.g., shown as an evolved packet core (EPC)) coupledtogether through an S1 interface 115. For convenience and brevity sake,only a portion of the core network 120, as well as the RAN 101, isshown. In a non-limiting example, the RAN 101 may be an evolveduniversal terrestrial radio access network (E-UTRAN). In anothernon-limiting example, the RAN 101 may include one or more components ofa New Radio (NR) network. In another non-limiting example, the RAN 101may include one or more components of an E-UTRAN and one or morecomponents of another network (including but not limited to an NRnetwork).

The core network 120 may include a mobility management entity (MME) 122,a serving gateway (serving GW) 124, and packet data network gateway (PDNGW) 126. In some embodiments, the network 100 may include (and/orsupport) one or more Evolved Node-B's (eNBs) 104 (which may operate asbase stations) for communicating with User Equipment (UE) 102. The eNBs104 may include macro eNBs and low power (LP) eNBs, in some embodiments.

In some embodiments, the network 100 may include (and/or support) one ormore Generation Node-B's (gNBs) 105. In some embodiments, one or moreeNBs 104 may be configured to operate as gNBs 105. Embodiments are notlimited to the number of eNBs 104 shown in FIG. 1A or to the number ofgNBs 105 shown in FIG. 1A. In some embodiments, the network 100 may notnecessarily include eNBs 104. Embodiments are also not limited to theconnectivity of components shown in FIG. 1A.

It should be noted that references herein to an eNB 104 or to a gNB 105are not limiting. In some embodiments, one or more operations, methodsand/or techniques (such as those described herein) may be practiced by abase station component (and/or other component), including but notlimited to a gNB 105, an eNB 104, a serving cell, a transmit receivepoint (TRP) and/or other. In some embodiments, the base stationcomponent may be configured to operate in accordance with a New Radio(NR) protocol and/or NR standard, although the scope of embodiments isnot limited in this respect. In some embodiments, the base stationcomponent may be configured to operate in accordance with a FifthGeneration (5G) protocol and/or 5G standard, although the scope ofembodiments is not limited in this respect.

In some embodiments, one or more of the UEs 102 and/or eNBs 104 may beconfigured to operate in accordance with an NR protocol and/or NRtechniques. References to a UE 102, eNB 104 and/or gNB 105 as part ofdescriptions herein are not limiting. For instance, descriptions of oneor more operations, techniques and/or methods practiced by a gNB 105 arenot limiting. In some embodiments, one or more of those operations,techniques and/or methods may be practiced by an eNB 104 and/or otherbase station component.

In some embodiments, the UE 102 may transmit signals (data, controland/or other) to the gNB 105, and may receive signals (data, controland/or other) from the gNB 105. In some embodiments, the UE 102 maytransmit signals (data, control and/or other) to the eNB 104, and mayreceive signals (data, control and/or other) from the eNB 104. Theseembodiments will be described in more detail below.

The MME 122 is similar in function to the control plane of legacyServing GPRS Support Nodes (SGSN). The MME 122 manages mobility aspectsin access such as gateway selection and tracking area list management.The serving GW 124 terminates the interface toward the RAN 101, androutes data packets between the RAN 101 and the core network 120. Inaddition, it may be a local mobility anchor point for inter-eNBhandovers and also may provide an anchor for inter-3GPP mobility. Otherresponsibilities may include lawful intercept, charging, and some policyenforcement. The serving GW 124 and the MME 122 may be implemented inone physical node or separate physical nodes. The PDN GW 126 terminatesan SGi interface toward the packet data network (PDN). The PDN GW 126routes data packets between the EPC 120 and the external PDN, and may bea key node for policy enforcement and charging data collection. It mayalso provide an anchor point for mobility with non-LTE accesses. Theexternal PDN can be any kind of IP network, as well as an IP MultimediaSubsystem (IMS) domain. The PDN GW 126 and the serving GW 124 may beimplemented in one physical node or separated physical nodes.

In some embodiments, the eNBs 104 (macro and micro) terminate the airinterface protocol and may be the first point of contact for a UE 102.In some embodiments, an eNB 104 may fulfill various logical functionsfor the network 100, including but not limited to RNC (radio networkcontroller functions) such as radio bearer management, uplink anddownlink dynamic radio resource management and data packet scheduling,and mobility management.

In some embodiments. UEs 102 may be configured to communicate OrthogonalFrequency Division Multiplexing (OFDM) communication signals with an eNB104 and/or gNB 105 over a multicarrier communication channel inaccordance with an Orthogonal Frequency Division Multiple Access (OFDMA)communication technique. In some embodiments, eNBs 104 and/or gNBs 105may be configured to communicate OFDM communication signals with a UE102 over a multicarrier communication channel in accordance with anOFDMA communication technique. The OFDM signals may comprise a pluralityof orthogonal subcarriers.

The S1 interface 115 is the interface that separates the RAN 101 and theEPC 120. It may be split into two parts: the S1-U1, which carriestraffic data between the eNBs 104 and the serving GW 124, and theS1-MME, which is a signaling interface between the eNBs 104 and the MME122. The X2 interface is the interface between eNBs 104. The X2interface comprises two parts, the X2-C and X2-U. The X2-C is thecontrol plane interface between the eNBs 104, while the X2-U is the userplane interface between the eNBs 104.

In some embodiments, similar functionality and/or connectivity describedfor the eNB 104 may be used for the gNB 105, although the scope ofembodiments is not limited in this respect. In a non-limiting example,the S1 interface 115 (and/or similar interface) may be split into twoparts: the S1-U, which carries traffic data between the gNBs 105 and theserving GW 124, and the S1-MME, which is a signaling interface betweenthe gNBs 104 and the MME 122. The X2 interface (and/or similarinterface) may enable communication between eNBs 104, communicationbetween gNBs 105 and/or communication between an eNB 104 and a gNB 105.

With cellular networks, LP cells are typically used to extend coverageto indoor areas where outdoor signals do not reach well, or to addnetwork capacity in areas with very dense phone usage, such as trainstations. As used herein, the term low power (LP) eNB refers to anysuitable relatively low power eNB for implementing a narrower cell(narrower than a macro cell) such as a femtocell, a picocell, or a microcell. Femtocell eNBs are typically provided by a mobile network operatorto its residential or enterprise customers. A femtocell is typically thesize of a residential gateway or smaller and generally connects to theuser's broadband line. Once plugged in, the femtocell connects to themobile operator's mobile network and provides extra coverage in a rangeof typically 30 to 50 meters for residential femtocells. Thus, a LP eNBmight be a femtocell eNB since it is coupled through the PDN GW 126.Similarly, a picocell as a wireless communication system typicallycovering a small area, such as in-building (offices, shopping malls,train stations, etc.), or more recently in-aircraft. A picocell eNB cangenerally connect through the X2 link to another eNB such as a macro eNBthrough its base station controller (BSC) functionality. Thus. LP eNBmay be implemented with a picocell eNB since it is coupled to a macroeNB via an X2 interface. Picocell eNBs or other LP eNBs may incorporatesome or all functionality of a macro eNB. In some cases, this may bereferred to as an access point base station or enterprise femtocell. Insome embodiments, various types of gNBs 105 may be used, including butnot limited to one or more of the eNB types described above.

In some embodiments, the network 150 may include one or more componentsconfigured to operate in accordance with one or more 3GPP standards,including but not limited to an NR standard. The network 150 shown inFIG. 1B may include a next generation RAN (NG-RAN) 155, which mayinclude one or more gNBs 105. In some embodiments, the network 150 mayinclude the E-UTRAN 160, which may include one or more eNBs. The E-UTRAN160 may be similar to the RAN 101 described herein, although the scopeof embodiments is not limited in this respect.

In some embodiments, the network 150 may include the MME 165. The MME165 may be similar to the MME 122 described herein, although the scopeof embodiments is not limited in this respect. The MME 165 may performone or more operations or functionality similar to those describedherein regarding the MME 122, although the scope of embodiments is notlimited in this respect.

In some embodiments, the network 150 may include the SGW 170. The SGW170 may be similar to the SGW 124 described herein, although the scopeof embodiments is not limited in this respect. The SGW 170 may performone or more operations or functionality similar to those describedherein regarding the SGW 124, although the scope of embodiments is notlimited in this respect.

In some embodiments, the network 150 may include component(s) and/ormodule(s) for functionality for a user plane function (UPF) and userplane functionality for PGW (PGW-U), as indicated by 175. In someembodiments, the network 150 may include component(s) and/or module(s)for functionality for a session management function (SMF) and controlplane functionality for PGW (PGW-C), as indicated by 180. In someembodiments, the component(s) and/or module(s) indicated by 175 and/or180 may be similar to the PGW 126 described herein, although the scopeof embodiments is not limited in this respect. The component(s) and/ormodule(s) indicated by 175 and/or 180 may perform one or more operationsor functionality similar to those described herein regarding the PGW126, although the scope of embodiments is not limited in this respect.One or both of the components 170, 172 may perform at least a portion ofthe functionality described herein for the POW 126, although the scopeof embodiments is not limited in this respect.

Embodiments are not limited to the number or type of components shown inFIG. 1B. Embodiments are also not limited to the connectivity ofcomponents shown in FIG. 1B.

In some embodiments, a downlink resource grid may be used for downlinktransmissions from an eNB 104 to a UE 102, while uplink transmissionfrom the UE 102 to the eNB 104 may utilize similar techniques. In someembodiments, a downlink resource grid may be used for downlinktransmissions from a gNB 105 to a UE 102, while uplink transmission fromthe UE 102 to the gNB 105 may utilize similar techniques. The grid maybe a time-frequency grid, called a resource grid or time-frequencyresource grid, which is the physical resource in the downlink in eachslot. Such a time-frequency plane representation is a common practicefor OFDM systems, which makes it intuitive for radio resourceallocation. Each column and each row of the resource grid correspond toone OFDM symbol and one OFDM subcarrier, respectively. The duration ofthe resource grid in the time domain corresponds to one slot in a radioframe. The smallest time-frequency unit in a resource grid is denoted asa resource element (RE). There are several different physical downlinkchannels that are conveyed using such resource blocks. With particularrelevance to this disclosure, two of these physical downlink channelsare the physical downlink shared channel and the physical down linkcontrol channel.

As used herein, the term “circuitry” may refer to, be part of, orinclude an Application Specific Integrated Circuit (ASIC), an electroniccircuit, a processor (shared, dedicated, or group), and/or memory(shared, dedicated, or group) that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablehardware components that provide the described functionality. In someembodiments, the circuitry may be implemented in, or functionsassociated with the circuity may be implemented by, one or more softwareor firmware modules. In some embodiments, circuitry may include logic,at least partially operable in hardware. Embodiments described hereinmay be implemented into a system using any suitably configured hardwareand/or software.

FIG. 2 illustrates a block diagram of an example machine in accordancewith some embodiments. The machine 200 is an example machine upon whichany one or more of the techniques and/or methodologies discussed hereinmay be performed. In alternative embodiments, the machine 200 mayoperate as a standalone device or may be connected (e.g., networked) toother machines. In a networked deployment, the machine 200 may operatein the capacity of a server machine, a client machine, or both inserver-client network environments. In an example, the machine 200 mayact as a peer machine in peer-to-peer (P2P) (or other distributed)network environment. The machine 200 may be a UE 102, eNB 104, gNB 105,access point (AP), station (STA), user, device, mobile device, basestation, personal computer (PC), a tablet PC, a set-top box (STB), apersonal digital assistant (PDA), a mobile telephone, a smart phone, aweb appliance, a network router, switch or bridge, or any machinecapable of executing instructions (sequential or otherwise) that specifyactions to be taken by that machine. Further, while only a singlemachine is illustrated, the term “machine” shall also be taken toinclude any collection of machines that individually or jointly executea set (or multiple sets) of instructions to perform any one or more ofthe methodologies discussed herein, such as cloud computing, software asa service (SaaS), other computer cluster configurations.

Examples as described herein, may include, or may operate on, logic or anumber of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operations andmay be configured or arranged in a certain manner. In an example,circuits may be arranged (e.g., internally or with respect to externalentities such as other circuits) in a specified manner as a module. Inan example, the whole or part of one or more computer systems (e.g., astandalone, client or server computer system) or one or more hardwareprocessors may be configured by firmware or software (e.g.,instructions, an application portion, or an application) as a modulethat operates to perform specified operations. In an example, thesoftware may reside on a machine readable medium. In an example, thesoftware, when executed by the underlying hardware of the module, causesthe hardware to perform the specified operations.

Accordingly, the term “module” is understood to encompass a tangibleentity, be that an entity that is physically constructed, specificallyconfigured (e.g., hardwired), or temporarily (e.g., transitorily)configured (e.g., programmed) to operate in a specified manner or toperform part or all of any operation described herein. Consideringexamples in which modules are temporarily configured, each of themodules need not be instantiated at any one moment in time. For example,where the modules comprise a general-purpose hardware processorconfigured using software, the general-purpose hardware processor may beconfigured as respective different modules at different times. Softwaremay accordingly configure a hardware processor, for example, toconstitute a particular module at one instance of time and to constitutea different module at a different instance of time.

The machine (e.g., computer system) 200 may include a hardware processor202 (e.g., a central processing unit (CPU), a graphics processing unit(GPU), a hardware processor core, or any combination thereof), a mainmemory 204 and a static memory 206, some or all of which may communicatewith each other via an interlink (e.g., bus) 208. The machine 200 mayfurther include a display unit 210, an alphanumeric input device 212(e.g., a keyboard), and a user interface (UI) navigation device 214(e.g., a mouse). In an example, the display unit 210, input device 212and U1 navigation device 214 may be a touch screen display. The machine200 may additionally include a storage device (e.g., drive unit) 216, asignal generation device 218 (e.g., a speaker), a network interfacedevice 220, and one or more sensors 221, such as a global positioningsystem (GPS) sensor, compass, accelerometer, or other sensor. Themachine 200 may include an output controller 228, such as a serial(e.g., universal serial bus (USB), parallel, or other wired or wireless(e.g., infrared (IR), near field communication (NFC), etc.) connectionto communicate or control one or more peripheral devices (e.g., aprinter, card reader, etc.).

The storage device 216 may include a machine readable medium 222 onwhich is stored one or more sets of data structures or instructions 224(e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 224 may alsoreside, completely or at least partially, within the main memory 204,within static memory 206, or within the hardware processor 202 duringexecution thereof by the machine 200. In an example, one or anycombination of the hardware processor 202, the main memory 204, thestatic memory 206, or the storage device 216 may constitute machinereadable media. In some embodiments, the machine readable medium may beor may include a non-transitory computer-readable storage medium. Insome embodiments, the machine readable medium may be or may include acomputer-readable storage medium.

While the machine readable medium 222 is illustrated as a single medium,the term “machine readable medium” may include a single medium ormultiple media (e.g., a centralized or distributed database, and/orassociated caches and servers) configured to store the one or moreinstructions 224. The term “machine readable medium” may include anymedium that is capable of storing, encoding, or carrying instructionsfor execution by the machine 200 and that cause the machine 200 toperform any one or more of the techniques of the present disclosure, orthat is capable of storing, encoding or carrying data structures used byor associated with such instructions. Non-limiting machine readablemedium examples may include solid-state memories, and optical andmagnetic media. Specific examples of machine readable media may include:non-volatile memory, such as semiconductor memory devices (e.g.,Electrically Programmable Read-Only Memory (EPROM). ElectricallyErasable Programmable Read-Only Memory (EEPROM)) and flash memorydevices; magnetic disks, such as internal hard disks and removabledisks; magneto-optical disks; Random Access Memory (RAM); and CD-ROM andDVD-ROM disks. In some examples, machine readable media may includenon-transitory machine readable media. In some examples, machinereadable media may include machine readable media that is not atransitory propagating signal.

The instructions 224 may further be transmitted or received over acommunications network 226 using a transmission medium via the networkinterface device 220 utilizing any one of a number of transfer protocols(e.g., frame relay, internet protocol (IP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks). Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards known as Wi-Fi®, IEEE 802.16 family ofstandards known as WiMax-X), IEEE 802.15.4 family of standards, a LongTerm Evolution (LTE) family of standards, a Universal MobileTelecommunications System (UMTS) family of standards, peer-to-peer (P2P)networks, among others. In an example, the network interface device 220may include one or more physical jacks (e.g., Ethernet, coaxial, orphone jacks) or one or more antennas to connect to the communicationsnetwork 226. In an example, the network interface device 220 may includea plurality of antennas to wirelessly communicate using at least one ofsingle-input multiple-output (SIMO), multiple-input multiple-output(MIMO), or multiple-input single-output (MISO) techniques. In someexamples, the network interface device 220 may wirelessly communicateusing Multiple User MIMO techniques. The term “transmission medium”shall be taken to include any intangible medium that is capable ofstoring, encoding or carrying instructions for execution by the machine200, and includes digital or analog communications signals or otherintangible medium to facilitate communication of such software.

FIG. 3 illustrates a user device in accordance with some aspects. Insome embodiments, the user device 300 may be a mobile device. In someembodiments, the user device 300 may be or may be configured to operateas a User Equipment (UE). In some embodiments, the user device 300 maybe arranged to operate in accordance with a new radio (NR) protocol. Insome embodiments, the user device 300 may be arranged to operate inaccordance with a Third Generation Partnership Protocol (3GPP) protocol.The user device 300 may be suitable for use as a UE 102 as depicted inFIG. 1 , in some embodiments. It should be noted that in someembodiments, a UE, an apparatus of a UE, a user device or an apparatusof a user device may include one or more of the components shown in oneor more of FIGS. 2, 3, and 5 . In some embodiments, such a UE, userdevice and/or apparatus may include one or more additional components.

In some aspects, the user device 300 may include an applicationprocessor 305, baseband processor 310 (also referred to as a basebandmodule), radio front end module (RFEM) 315, memory 320, connectivitymodule 325, near field communication (NFC) controller 330, audio driver335, camera driver 340, touch screen 345, display driver 350, sensors355, removable memory 360, power management integrated circuit (PMIC)365 and smart battery 370. In some aspects, the user device 300 may be aUser Equipment (UE).

In some aspects, application processor 305 may include, for example, oneor more CPU cores and one or more of cache memory, low drop-out voltageregulators (LDOs), interrupt controllers, serial interfaces such asserial peripheral interface (SPI), inter-integrated circuit (I²C) oruniversal programmable serial interface module, real time clock (RTC),timer-counters including interval and watchdog timers, general purposeinput-output (IO), memory card controllers such as securedigital/multi-media card (SD/MMC) or similar, universal serial bus (USB)interfaces, mobile industry processor interface (MIPI) interfaces andJoint Test Access Group (JTAG) test access ports.

In some aspects, baseband module 310 may be implemented, for example, asa solder-down substrate including one or more integrated circuits, asingle packaged integrated circuit soldered to a main circuit board,and/or a multi-chip module containing two or more integrated circuits.

FIG. 4 illustrates a base station in accordance with some aspects. Insome embodiments, the base station 400 may be or may be configured tooperate as an Evolved Node-B (eNB). In some embodiments, the basestation 400 may be or may be configured to operate as a GenerationNode-B (gNB). In some embodiments, the base station 400 may be arrangedto operate in accordance with a new radio (NR) protocol. In someembodiments, the base station 400 may be arranged to operate inaccordance with a Third Generation Partnership Protocol (3GPP) protocol.It should be noted that in some embodiments, the base station 400 may bea stationary non-mobile device. The base station 400 may be suitable foruse as an eNB 104 as depicted in FIG. 1 , in some embodiments. The basestation 400 may be suitable for use as a gNB 105 as depicted in FIG. 1 ,in some embodiments. It should be noted that in some embodiments, aneNB, an apparatus of an eNB, a gNB, an apparatus or a gNB, a basestation and/or an apparatus of a base station may include one or more ofthe components shown in one or more of FIGS. 2, 4, and 5 . In someembodiments, such an eNB, gNB, base station and/or apparatus may includeone or more additional components.

FIG. 4 illustrates a base station or infrastructure equipment radio head400 in accordance with an aspect. The base station 400 may include oneor more of application processor 405, baseband modules 410, one or moreradio front end modules 415, memory 420, power management circuitry 425,power tee circuitry 430, network controller 435, network interfaceconnector 440, satellite navigation receiver module 445, and userinterface 450. In some aspects, the base station 400 may be an EvolvedNode-B (eNB), which may be arranged to operate in accordance with a 3GPPprotocol, new radio (NR) protocol and/or Fifth Generation (5G) protocol.In some aspects, the base station 400 may be a generation Node-B (gNB),which may be arranged to operate in accordance with a 3GPP protocol, newradio (NR) protocol and/or Fifth Generation (5G) protocol.

In some aspects, application processor 405 may include one or more CPUcores and one or more of cache memory, low drop-out voltage regulators(LDOs), interrupt controllers, serial interfaces such as SPI. I²C oruniversal programmable serial interface module, real time clock (RTC),timer-counters including interval and watchdog timers, general purposeIO, memory card controllers such as SD/MMC or similar, USB interfaces.MIPI interfaces and Joint Test Access Group (JTAG) test access ports.

In some aspects, baseband processor 410 may be implemented, for example,as a solder-down substrate including one or more integrated circuits, asingle packaged integrated circuit soldered to a main circuit board or amulti-chip module containing two or more integrated circuits.

In some aspects, memory 420 may include one or more of volatile memoryincluding dynamic random access memory (DRAM) and/or synchronous dynamicrandom access memory (SDRAM), and nonvolatile memory (NVM) includinghigh-speed electrically erasable memory (commonly referred to as Flashmemory), phase change random access memory (PRAM), magneto-resistiverandom access memory (MRAM) and/or a three-dimensional cross-pointmemory. Memory 420 may be implemented as one or more of solder downpackaged integrated circuits, socketed memory modules and plug-in memorycards.

In some aspects, power management integrated circuitry 425 may includeone or more of voltage regulators, surge protectors, power alarmdetection circuitry and one or more backup power sources such as abattery or capacitor. Power alarm detection circuitry may detect one ormore of brown out (under-voltage) and surge (over-voltage) conditions.

In some aspects, power tee circuitry 430 may provide for electricalpower drawn from a network cable to provide both power supply and dataconnectivity to the base station 400 using a single cable. In someaspects, network controller 435 may provide connectivity to a networkusing a standard network interface protocol such as Ethernet. Networkconnectivity may be provided using a physical connection which is one ofelectrical (commonly referred to as copper interconnect), optical orwireless.

In some aspects, satellite navigation receiver module 445 may includecircuitry to receive and decode signals transmitted by one or morenavigation satellite constellations such as the global positioningsystem (GPS). Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS).Galileo and/or BeiDou. The receiver 445 may provide data to applicationprocessor 405 which may include one or more of position data or timedata. Application processor 405 may use time data to synchronizeoperations with other radio base stations. In some aspects, userinterface 450 may include one or more of physical or virtual buttons,such as a reset button, one or more indicators such as light emittingdiodes (LEDs) and a display screen.

FIG. 5 illustrates an exemplary communication circuitry according tosome aspects. Circuitry 500 is alternatively grouped according tofunctions. Components as shown in 500 are shown here for illustrativepurposes and may include other components not shown here in FIG. 5 . Insome aspects, the communication circuitry 500 may be used for millimeterwave communication, although aspects are not limited to millimeter wavecommunication. Communication at any suitable frequency may be performedby the communication circuitry 500 in some aspects.

It should be noted that a device, such as a UE 102, eNB 104, gNB 105,the user device 300, the base station 400, the machine 200 and/or otherdevice may include one or more components of the communication circuitry500, in some aspects.

The communication circuitry 500 may include protocol processingcircuitry 505, which may implement one or more of medium access control(MAC), radio link control (RLC), packet data convergence protocol(PDCP), radio resource control (RRC) and non-access stratum (NAS)functions. Protocol processing circuitry 505 may include one or moreprocessing cores (not shown) to execute instructions and one or morememory structures (not shown) to store program and data information.

The communication circuitry 500 may further include digital basebandcircuitry 510, which may implement physical layer (PHY) functionsincluding one or more of hybrid automatic repeat request (HARQ)functions, scrambling and/or descrambling, coding and/or decoding, layermapping and/or de-mapping, modulation symbol mapping, received symboland/or bit metric determination, multi-antenna port pre-coding and/ordecoding which may include one or more of space-time, space-frequency orspatial coding, reference signal generation and/or detection, preamblesequence generation and/or decoding, synchronization sequence generationand/or detection, control channel signal blind decoding, and otherrelated functions.

The communication circuitry 500 may further include transmit circuitry515, receive circuitry 520 and/or antenna array circuitry 530. Thecommunication circuitry 500 may further include radio frequency (RF)circuitry 525. In an aspect of the disclosure, RF circuitry 525 mayinclude multiple parallel RF chains for one or more of transmit orreceive functions, each connected to one or more antennas of the antennaarray 530.

In an aspect of the disclosure, protocol processing circuitry 505 mayinclude one or more instances of control circuitry (not shown) toprovide control functions for one or more of digital baseband circuitry510, transmit circuitry 515, receive circuitry 520, and/or radiofrequency circuitry 525

In some embodiments, processing circuitry may perform one or moreoperations described herein and/or other operation(s) In a non-limitingexample, the processing circuitry may include one or more componentssuch as the processor 202, application processor 305, baseband module310, application processor 405, baseband module 410, protocol processingcircuitry 505, digital baseband circuitry 510, similar component(s)and/or other component(s).

In some embodiments, a transceiver may transmit one or more elements(including but not limited to those described herein) and/or receive oneor more elements (including but not limited to those described herein).In a non-limiting example, the transceiver may include one or morecomponents such as the radio front end module 315, radio front endmodule 415, transmit circuitry 515, receive circuitry 520, radiofrequency circuitry 525, similar component(s) and/or other component(s).

One or more antennas (such as 230, 312, 412, 530 and/or others) maycomprise one or more directional or omnidirectional antennas, including,for example, dipole antennas, monopole antennas, patch antennas, loopantennas, microstrip antennas or other types of antennas suitable fortransmission of RF signals. In some multiple-input multiple-output(MIMO) embodiments, one or more of the antennas (such as 230, 312, 412,530 and/or others) may be effectively separated to take advantage ofspatial diversity and the different channel characteristics that mayresult.

In some embodiments, the UE 102, eNB 104, gNB 105, user device 300, basestation 400, machine 200 and/or other device described herein may be amobile device and/or portable wireless communication device, such as apersonal digital assistant (PDA), a laptop or portable computer withwireless communication capability, a web tablet, a wireless telephone, asmartphone, a wireless headset, a pager, an instant messaging device, adigital camera, an access point, a television, a wearable device such asa medical device (e.g., a heart rate monitor, a blood pressure monitor,etc.), or other device that may receive and/or transmit informationwirelessly. In some embodiments, the UE 102, eNB 104, gNB 105, userdevice 300, base station 400, machine 200 and/or other device describedherein may be configured to operate in accordance with 3GPP standards,although the scope of the embodiments is not limited in this respect. Insome embodiments, the UE 102, eNB 104, gNB 105, user device 300, basestation 400, machine 200 and/or other device described herein may beconfigured to operate in accordance with new radio (NR) standards,although the scope of the embodiments is not limited in this respect. Insome embodiments, the UE 102, eNB 104, gNB 105, user device 300, basestation 400, machine 200 and/or other device described herein may beconfigured to operate according to other protocols or standards,including IEEE 802.11 or other IEEE standards. In some embodiments, theUE 102, eNB 104, gNB 105, user device 300, base station 400, machine 200and/or other device described herein may include one or more of akeyboard, a display, a non-volatile memory port, multiple antennas, agraphics processor, an application processor, speakers, and other mobiledevice elements. The display may be an LCD screen including a touchscreen.

Although the UE 102, eNB 104, gNB 105, user device 300, base station400, machine 200 and/or other device described herein may each beillustrated as having several separate functional elements, one or moreof the functional elements may be combined and may be implemented bycombinations of software-configured elements, such as processingelements including digital signal processors (DSPs), and/or otherhardware elements. For example, some elements may comprise one or moremicroprocessors, DSPs, field-programmable gate arrays (FPGAs),application specific integrated circuits (ASICs), radio-frequencyintegrated circuits (RFICs) and combinations of various hardware andlogic circuitry for performing at least the functions described herein.In some embodiments, the functional elements may refer to one or moreprocesses operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage device, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage device may include anynon-transitory mechanism for storing information in a form readable by amachine (e.g., a computer). For example, a computer-readable storagedevice may include read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media. Some embodiments mayinclude one or more processors and may be configured with instructionsstored on a computer-readable storage device.

It should be noted that in some embodiments, an apparatus used by the UE102, eNB 104, gNB 105, machine 200, user device 300 and/or base station400 may include various components shown in FIGS. 2-5 . Accordingly,techniques and operations described herein that refer to the UE 102 maybe applicable to an apparatus of a UE. In addition, techniques andoperations described herein that refer to the eNB 104 may be applicableto an apparatus of an eNB. In addition, techniques and operationsdescribed herein that refer to the gNB 105 may be applicable to anapparatus of a gNB.

FIG. 6 illustrates an example of a radio frame structure in accordancewith some embodiments. FIGS. 7A and 7B illustrate example frequencyresources in accordance with some embodiments. In references herein,“FIG. 7 ” may include FIG. 7A and FIG. 7B. It should be noted that theexamples shown in FIGS. 6-7 may illustrate some or all of the conceptsand techniques described herein in some cases, but embodiments are notlimited by the examples. For instance, embodiments are not limited bythe name, number, type, size, ordering, arrangement and/or other aspectsof the time resources, symbol periods, frequency resources, PRBs andother elements as shown in FIGS. 6-7 . Although some of the elementsshown in the examples of FIGS. 6-7 may be included in a 3GPP LTEstandard, 5G standard. NR standard and/or other standard, embodimentsare not limited to usage of such elements that are included instandards.

An example of a radio frame structure that may be used in some aspectsis shown in FIG. 6 . In this example, radio frame 600 has a duration of10 ms. Radio frame 600 is divided into slots 602 each of duration 0.5ms, and numbered from 0 to 19. Additionally, each pair of adjacent slots602 numbered 2i and 2i+1, where i is an integer, is referred to as asubframe 601.

In some aspects using the radio frame format of FIG. 6 , each subframe601 may include a combination of one or more of downlink controlinformation, downlink data information, uplink control information anduplink data information. The combination of information types anddirection may be selected independently for each subframe 602.

Referring to FIGS. 7A and 7B, in some aspects, a sub-component of atransmitted signal consisting of one subcarrier in the frequency domainand one symbol interval in the time domain may be termed a resourceelement. Resource elements may be depicted in a grid form as shown inFIG. 7A and FIG. 7B.

In some aspects, illustrated in FIG. 7A, resource elements may begrouped into rectangular resource blocks 700 consisting of 12subcarriers in the frequency domain and the P symbols in the timedomain, where P may correspond to the number of symbols contained in oneslot, and may be 6, 7, or any other suitable number of symbols.

In some alternative aspects, illustrated in FIG. 7B, resource elementsmay be grouped into resource blocks 700 consisting of 12 subcarriers (asindicated by 702) in the frequency domain and one symbol in the timedomain. In the depictions of FIG. 7A and FIG. 7B, each resource element705 may be indexed as (k, 1) where k is the index number of subcarrier,in the range 0 to N-M-1 (as indicated by 703), where N is the number ofsubcarriers in a resource block, and M is the number of resource blocksspanning a component carrier in the frequency domain.

In accordance with some embodiments, the UE 102 may select, from aplurality of short transmission time intervals (TTIs), a short TTI for avehicle-to-vehicle (V2V) sidelink transmission b) the UE 102. The shortTTIs may occur within a legacy TTI. The short TTIs may be allocated forV2V sidelink transmissions by non-legacy UEs 102. The legacy TTI may beallocated for V2V sidelink transmissions by legacy UEs 102. The UE 102may transmit, in accordance with the legacy TTI, a legacy physicalsidelink control channel (PSCCH) to indicate, to legacy UEs 102, the V2Vsidelink transmission by the UE 102. The UE 102 may transmit, inaccordance with the selected short TTI, a short PSCCH (sPSCCH) toindicate, to non-legacy UEs 102, the V2V sidelink transmission by the UE102. These embodiments are described in more detail below.

FIG. 8 illustrates the operation of a method of communication inaccordance with some embodiments. In describing the method 800,reference may be made to one or more of FIGS. 1-23 , although it isunderstood that the method 800 may be practiced with any other suitablesystems, interfaces and components. In some cases, descriptions hereinof one or more of the concepts, operations and/or techniques regardingone of the methods described herein (800 and/or other) may be applicableto at least one of the other methods described herein (800 and/orother).

Some embodiments of the method 800 may include additional operations incomparison to what is illustrated in FIG. 8 , including but not limitedto operations described herein. Some embodiments of the method 800 maynot necessarily include all of the operations shown in FIG. 8 . Inaddition, embodiments of the method 800 are not necessarily limited tothe chronological order that is shown in FIG. 8 . In some embodiments, aUE 102 may perform one or more operations of the method 800, butembodiments are not limited to performance of the method 800 and/oroperations of it by the UE 102. Accordingly, although references may bemade to performance of one or more operations of the method 800 by theUE 102 in descriptions herein, it is understood that the gNB 105 and/oreNB 104 may perform one or more operations that may be the same as,similar to and/or reciprocal to one or more of the operations of themethod 800, in some embodiments.

While the method 800 and other methods described herein may refer toeNBs 104, gNBs 105 or UEs 102 operating in accordance with 3GPPstandards, 5G standards. NR standards and/or other standards,embodiments of those methods are not limited to just those eNBs 104,gNBs 105 or UEs 102 and may also be practiced on other devices, such asa Wi-Fi access point (AP) or user station (STA). In addition, the method800 and other methods described herein may be practiced by wirelessdevices configured to operate in other suitable types of wirelesscommunication systems, including systems configured to operate accordingto various IEEE standards such as IEEE 802.11. The methods 800 and othermethods described herein may also be applicable to an apparatus of a UE102, an apparatus of an eNB 104, an apparatus of a gNB 105 and/or anapparatus of another device described above.

It should also be noted that embodiments are not limited by referencesherein (such as in descriptions of the method and/or other descriptionsherein) to transmission, reception and/or exchanging of elements such asframes, messages, requests, indicators, signals or other elements. Insome embodiments, such an element may be generated, encoded or otherwiseprocessed by processing circuitry (such as by a baseband processorincluded in the processing circuitry) for transmission. The transmissionmay be performed by a transceiver or other component, in some cases. Insome embodiments, such an element may be decoded, detected or otherwiseprocessed by the processing circuitry (such as by the basebandprocessor). The element may be received by a transceiver or othercomponent, in some cases. In some embodiments, the processing circuitryand the transceiver may be included in a same apparatus. The scope ofembodiments is not limited in this respect, however, as the transceivermay be separate from the apparatus that comprises the processingcircuitry, in some embodiments.

One or more of the messages described herein may be included in astandard and/or protocol, including but not limited to Third GenerationPartnership Project (3GPP), 3GPP Long Term Evolution (LTE), FourthGeneration (4G), Fifth Generation (5G), New Radio (NR) and/or other. Thescope of embodiments is not limited to usage of elements that areincluded in standards, however.

At operation 805, the UE 102 may receive one or more control messagesthat indicate an allocation of a resource pool for V2V sidelinktransmissions. In some embodiments, the one or more control messages maybe received from the eNB 104 and/or gNB 105, although the scope ofembodiments is not limited in this respect. Any suitable controlmessages may be used.

In some embodiments, the one or more control messages may includeinformation related to the allocation of the resource pool for V2Vsidelink transmissions. In some embodiments, such information may berelated to one or more of the operations described herein. In someembodiments, such information may be related to one or more of:transmission time intervals (TTIs), short TTIs, configuration of TTIs,configuration of short TTIs, resource pools, channel sensing, sensingwindow, resource selection window, resource (re)-selection window and/orother concepts (including but not limited to concepts described herein).

In some embodiments, a resource pool may be allocated for V2V sidelinktransmissions. In some embodiments, multiple resource pools may beallocated for V2V sidelink transmissions. In some embodiments, the eNB104 and/or gNB 105 may allocate the one or more resource pools, althoughthe scope of embodiments is not limited in this respect. Accordingly,the eNB 104 and/or gNB 105 may transmit one or more control messagesthat indicate information related to the resource pool(s). In someembodiments, the one or more resource pools may be allocated for V2Vsidelink transmissions in accordance with a 3GPP standard and/or otherstandard, although the scope of embodiments is not limited in thisrespect.

It should be noted that some embodiments may not necessarily includeoperation 805. In a non-limiting example, the resource pool(s) for V2Vsidelink transmissions may be pre-configured, pre-defined, included in astandard and/or other. The control messages of operation 805 may not benecessary in these and other scenarios.

It should be noted that descriptions herein may refer to V2V sidelinktransmissions, but embodiments are not limited to V2V sidelinktransmissions. One or more of the operations and/or techniques describedherein related to V2V sidelink transmissions may be applicable tosidelink transmissions that are not necessarily V2V sidelinktransmissions.

In some embodiments, a resource pool may include time resources and/orfrequency resources. In a non-limiting example, the resource pool mayinclude one or more physical resource blocks (PRBs) and one or moresymbol periods (including but not limited to OFDM symbol periods). Inanother non-limiting example, the resource pool may include one or moresub-channels and one or more sub-frames. In some embodiments, theresource pool may include contiguous frequency resources, sub-channelsand/or PRBs, although the scope of embodiments is not limited in thisrespect. In some embodiments, the resource pool may include contiguoustime resources, symbol periods and/or sub-frames, although the scope ofembodiments is not limited in this respect.

It should be noted that descriptions herein of some operations and/ortechniques may refer to PRBs, sub-channels, symbol periods and/orsub-frames, but such references are not limiting. In some embodiments,other time resources and/or frequency resources may be used in one ormore of those operations and/or techniques.

At operation 810, the UE 102 may determine one or more signal quality orsensing measurements. Non-limiting examples of the signal qualitymeasurements include a sidelink received signal strength indicator(S-RSSI), a received signal strength indicator (RSSI), a signal-to-noiseratio (SNR), a reference signal received power (RSRP), a referencesignal received quality (RSRQ), channel busy ratio (CBR) and/or other.

At operation 815, the UE 102 may select a short transmission timeinterval (TTI). In some embodiments, the UE 102 may select the short TTIfor a vehicle-to-vehicle (V2V) sidelink transmission by the UE 102. Insome embodiments, the UE 102 may select the short TTI from a pluralityof short TTIs (including but not limited to a plurality of candidateTTIs). In some embodiments, the UE 102 may select and/or use multipleshort TTIs for one or more V2V sidelink transmissions by the UE 102.

In some embodiments, the short TTIs may be allocated for V2V sidelinktransmissions by non-legacy UEs 102 and the legacy TTI may be allocatedfor V2V sidelink transmissions by legacy UEs 102. It should be notedthat references to a non-legacy UE 102 are not limiting. In someembodiments, an enhanced UE 102, a UE 102 configured for NR operation, aUE 102 configured for 5G operation and/or other type of UE 102 may beused. In a non-limiting example, an operation that is performed by anon-legacy UE 102 in descriptions herein may be performed by an enhancedUE 102, a UE 102 configured for NR operation, a UE 102 configured for 5Goperation and/or other type of UE 102, in some embodiments. In anothernon-limiting example, some scenarios may include communication between acomponent and a non-legacy UE 102 in descriptions herein. In someembodiments, same or similar scenarios may include communication betweenthe component and an enhanced UE 102, a UE 102 configured for NRoperation, a UE 102 configured for 5G operation and/or other type of UE102.

In some embodiments, the UE 102 may determine one or more signal qualitymeasurements for the plurality of short TTIs. The signal qualitymeasurements may be determined based on one or more channel senseoperations prior to the legacy TTI, although the scope of embodiments isnot limited in this respect. The UE 102 may select the short TTI for theV2V sidelink transmission based at least partly on the signal qualitymeasurements for the plurality of short TTIs.

It should be noted that references to a “short TTI” are not limiting.Such references may be used for clarity, in some cases. In someembodiments, one or more short TTIs may occur within a legacy TTI. Insome embodiments, one or more short TTIs may be within a legacy TTI. Insome embodiments, a legacy TTI may include multiple short TTIs. In someembodiments, a legacy TTI may be divided to include multiple short TTIs.The short TTI may be shorter than the legacy TTI, although the scope ofembodiments is not limited in this respect.

In a non-limiting example, the legacy TTI may be used in accordance witha legacy LTE protocol (including but not limited to LTE R14) and theshort TTI may be used in accordance with another LTE protocol (includingbut not limited to an enhanced LTE, LTE R15 and/or a later version ofLTE).

In another non-limiting example, the legacy TTI may span one millisecond(msec), and the plurality of short TTIs may include four short TTIs. Inanother non-limiting example, the legacy TTI may span one msec, and theplurality of short TTIs may include two short TTIs. Embodiments are notlimited by these example numbers.

In another non-limiting example, a short TTI may span a plurality ofsymbol periods. At least one of the symbol periods may be based ondemodulation reference signals (DMRS). At least one of the symbolperiods may be based on data bits.

In some embodiments, multiple legacy TTIs may be allocated for V2Vsidelink transmissions. In some cases, one or more of the legacy TTIsmay include multiple short TTIs. One or more of those short TTIs may beallocated for V2V sidelink transmissions, in some cases.

At operation 820, the UE 102 may transmit a legacy physical sidelinkcontrol channel (PSCCH). In some embodiments, the UE 102 may transmitthe legacy PSCCH to indicate, to legacy UEs 102, the V2V sidelink PSSCHtransmission by the UE 102. It should be noted that embodiments are notlimited to usage of the legacy PSCCH in this operation and/or otheroperations described herein, as any suitable element may be used. Itshould be noted that some embodiments may not necessarily includeoperation 820.

In some embodiments, the UE 102 may transmit the legacy PSCCH inaccordance with the legacy TTI, although the scope of embodiments is notlimited in this respect. In some embodiments, the UE 102 may transmitthe legacy PSCCH in the legacy TTI, although the scope of embodiments isnot limited in this respect. In some embodiments, the UE 102 maytransmit the legacy PSCCH and PSSCH within the legacy TTI, although thescope of embodiments is not limited in this respect.

At operation 825, the UE 102 may transmit a short PSCCH (sPSCCH). Atoperation 830, the UE 102 may transmit a short PSSCH (sPSSCH). In someembodiments, the UE 102 may transmit the sPSCCH to indicate, tonon-legacy UEs 102, the V2V sidelink transmission by the UE 102. In someembodiments, the V2V sidelink transmission may include transmission ofan sPSSCH or PSSCH. Embodiments are not limited to usage of an sPSSCH orPSSCH, however, as other elements may be used in some embodiments. Itshould be noted that embodiments are not limited to usage of the sPSCCHfor operation 825, as other elements (including other types of PSCCH)may be used, in some embodiments. The sPSCCH may be included in a 3GPPstandard, in some embodiments. It should be noted that embodiments arenot limited to usage of the sPSCCH in this operation and/or otheroperations described herein, as any suitable element may be used.

In some embodiments, the UE 102 may transmit the sPSCCH in accordancewith the selected short TTI, although the scope of embodiments is notlimited in this respect. In some embodiments, the UE 102 may transmitthe sPSCCH in the selected short TTI, although the scope of embodimentsis not limited in this respect. In some embodiments, the UE 102 maytransmit the sPSCCH within the selected short TTI, although the scope ofembodiments is not limited in this respect.

In some embodiments, multiple sPSCCHs may be transmitted. For instance,multiple short TTIs may be selected, and the UE 102 may transmitmultiple sPSCCHs per short TTI.

At operation 830, the UE 102 may transmit a short physical sidelinkshared channel (sPSSCH). In some embodiments, the UE 102 may transmitthe sPSSCH as part of the V2V sidelink transmission, although the scopeof embodiments is not limited in this respect. It should be noted thatembodiments are not limited to usage of the sPSSCH for operation 830, asother elements (including other types of PSSCH) may be used, in someembodiments. The sPSSCH may be included in a 3GPP standard, in someembodiments. It should be noted that embodiments are not limited tousage of the sPSSCH in this operation and/or other operations describedherein, as any suitable element may be used.

In some embodiments, the UE 102 may transmit the sPSSCH in accordancewith the selected short TTI, although the scope of embodiments is notlimited in this respect. In some embodiments, the UE 102 may transmitthe sPSSCH in the selected short TTI, although the scope of embodimentsis not limited in this respect. In some embodiments, the UE 102 maytransmit the sPSSCH within the selected short TTI, although the scope ofembodiments is not limited in this respect.

In a non-limiting example, the UE 102 may transmit the sPSSCH and thesPSCCH in separate frequency resources in accordance with a frequencydivision multiplexing (FDM) technique. In another non-limiting example,the UE 102 may transmit the sPSSCH in a short TTI that is later than theselected short TTI in accordance with a time division multiplexing (TDM)technique.

In another non-limiting example, the UE 102 may transmit the PSCCH infirst frequency resources allocated for V2V sidelink transmissions bylegacy UEs 102. The UE 102 may transmit the sPSCCH in second frequencyresources allocated for V2V sidelink transmissions by non-legacy UEs102.

In another non-limiting example, the sPSCCH may include a sidelinkcontrol information (SCI) that indicates first information related tothe V2V sidelink transmission by the UE 102. The legacy PSCCH mayinclude a sidelink control information (SCI) format-1 (SCI-F1) thatindicates second information related to the V2V sidelink transmission bythe UE 102. In some embodiments, the SCI and/or SCI-F1 may indicateresources of the V2V sidelink transmission by the UE 102, such asfrequency resources (PRBs, sub-channels and/or other) and/or timeresources (sub-frames, symbols and/or other).

At operation 835, the UE 102 may transmit an automatic gain control(AGC) element. In some embodiments, the UE 102 may transmit the AGCelement in a first chronological symbol period of the legacy TTI. Insome embodiments, the UE 102 may transmit the AGC element in the firstchronological symbol period of the legacy TTI independent of a positionof the selected TTI within the legacy TTI. In some embodiments, the UE102 may transmit the AGC element in a first chronological symbol periodof a sub-frame. In some cases, transmission of the AGC element in thefirst chronological symbol period may enable proper setting of the AGCfor legacy UEs 102 to avoid near-far problems and/or dynamic rangesaturation problems. In addition, transmission of the AGC element in thefirst chronological symbol period may help to reduce AGC implementationoverhead for multiple UEs 102, since the AGC may be settled at thebeginning of the legacy TTI.

In some embodiments, the AGC element may be transmitted to enable AGC atlegacy UEs 102. In some embodiments, the AGC element may be transmittedto enable AGC at non-legacy UEs 102. In some embodiments, the AGCelement may be transmitted to enable AGC at legacy UEs 102 and/ornon-legacy UEs 102.

In some embodiments, the AGC element may be based on a predeterminedsequence, although the scope of embodiments is not limited in thisrespect. In some embodiments, the AGC element may be transmitted duringa symbol period (such as an AGC symbol period) that may bededicated-reserved for transmission of the AGC element.

At operation 840, the UE 102 may select a resource pool from candidateresource pools. In some embodiments, the UE 102 may select the resourcepool for one or more V2V sidelink transmissions by the UE 102. In someembodiments, sub-frames of different candidate resource pools may benon-overlapping, although the scope of embodiments is not limited inthis respect.

In some embodiments, the candidate resource pools may be allocated forV2V transmissions of different latencies per candidate resource pool,although the scope of embodiments is not limited in this respect. Insome embodiments, the UE 102 may select the resource pool from thecandidate resource pools based at least partly on: a target latency ofthe V2V sidelink transmission by the UE 102, and the different latenciesper candidate resource pool. For instance, the UE 102 may select theresource pool for which a corresponding latency is the same as and/orclosest to a target latency of the UE 102. In a non-limiting example, afirst resource pool may be allocated for V2V sidelink transmissions ofrelatively high latency and a second resource pool may be allocated forV2V sidelink transmissions of a relatively low latency. For instance therelatively low latency may be 20 msec or less, although any suitablerange for the relatively low latency may be used.

It should be noted that some embodiments may not necessarily includeoperation 840. For instance, in some embodiments, a single resource poolmay be used, in which case the selection of operation 840 may not benecessary.

At operation 845, the UE 102 may monitor a sensing window for V2Vsidelink transmissions. In some embodiments, the sensing window mayoccur before the selected resource pool. In some embodiments, the UE 102may attempt to detect V2V sidelink transmissions by other UEs 102 duringthe sensing window. In some embodiments, candidate resource pools may beconfigured for sensing and/or resource selection windows of differentdurations.

In some embodiments, the UE 102 may determine one or more signal qualitymeasurements during the sensing window. Non-limiting examples of signalquality measurements include S-RSSI, SNR, RSRP. RSRQ and/or other. Insome embodiments, a resource pool may include multiple physical resourceblocks (PRBs) and/or sub-channels per sub-frame, and the radiomeasurement(s) may include a channel busy ratio (CBR). In a non-limitingexample, the CBR may be based at least partly on a ratio, for thePRBs/subchannels during a window of sub-frames, of: a total number ofPRBs/subchannels for which a signal quality measurement is above athreshold, and a total number of PRBs/subchannels.

At operation 850, the UE 102 may determine one or more availablesub-frames. At operation 855, the UE 102 may select one or moresub-frames based on the available sub-frames. At operation 860, the UE102 may transmit a PSSCH in the selected sub-frames.

In some embodiments, the UE 102 may determine one or more candidatesub-frames of a resource selection window available for the V2V sidelinktransmission by the UE 102. In a non-limiting example, one or more SCIsincluded in the detected V2V sidelink transmissions may be used for thedetermination of the candidate sub-frames. In another non-limitingexample, one or more signal quality measurements (including but notlimited to signal quality measurements determined during the sensingwindow) may be used for the determination of the candidate sub-frames.In some embodiments, the resource selection window may be subsequent tothe sensing window. In a non-limiting example, a duration of theresource selection window may be less than or equal to 10 sub-frames ordetermined by packet transmission latency or configured by UE higherlayers. Embodiments are not limited to this example number, as any sizemay be used for the selection window. It should be noted that theresource selection window may be related to one or more of: selection ofresources, re-selection of resources and/or other.

In some embodiments, the UE 102 may select, from the candidatesub-frames, one or more sub-frames for the V2V sidelink transmission bythe UE 102 in the resource selection window. The UE 102 may transmit, inthe selected sub-frames, a PSSCH based on a block of data bits.

In some embodiments, the UE 102 may select the one or more sub-framesfor V2V sidelink transmissions by the UE 102 in multiple selectionwindows that are shifted in time. In some embodiments, the UE 102 mayselect the one or more sub-frames for V2V sidelink transmissions by theUE 102 to include the candidate sub-frame that is earliest in theresource selection window. In some cases, this selection technique maybe referred to, without limitation, as a “first in time” selection orsimilar.

It should be noted that some embodiments may not necessarily include alloperations shown in FIG. 8 . In a non-limiting example, some operationsmay include one or more of operations 805-835, but may not necessarilyinclude one or more of operations 840-855. In another non-limitingexample, some operations may include one or more of operations 840-855,but may not necessarily include one or more of operations 805-835. Inanother non-limiting example, in embodiments in which the short TTI isnot used, the method 800 may not necessarily include one or more ofoperations 805-835.

In some embodiments, an apparatus of a UE 102 may comprise memory. Thememory may be configurable to store information that identifies theselected short TTI. The memory may store one or more other elements andthe apparatus may use them for performance of one or more operations.The apparatus may include processing circuitry, which may perform one ormore operations (including but not limited to operation(s) of the method800 and/or other methods described herein). The processing circuitry mayinclude a baseband processor. The baseband circuitry and/or theprocessing circuitry may perform one or more operations describedherein, including but not limited to selection of the short TTI for theV2V transmission. The apparatus of the UE 102 may include a transceiverto transmit the sPSCCH. The transceiver may transmit and/or receiveother blocks, messages and/or other elements.

FIGS. 9-11 illustrate example multiplexing arrangements that may be usedin accordance with some embodiments. FIGS. 12-17 illustrate examplearrangements that may be used in accordance with various transmissiontime intervals (TTIs) in accordance with some embodiments. FIGS. 18-19illustrate example resource assignments that may be used in accordancewith some embodiments. FIGS. 20-23 illustrate example techniques forresource selection in accordance with some embodiments.

It should be noted that the examples shown in FIGS. 9-23 may illustratesome or all of the concepts and techniques described herein in somecases, but embodiments are not limited by the examples. For instance,embodiments are not limited by the name, number, type, size, ordering,arrangement and/or other aspects of the operations, messages, timeintervals, symbols, eNBs 104, gNBs 105, UEs 102, and other elements asshown in FIGS. 9-23 . Although some of the elements shown in theexamples of FIGS. 9-23 may be included in a 3GPP LTE standard, 5Gstandard, NR standard and/or other standard, embodiments are not limitedto usage of such elements that are included in standards.

In some embodiments, sidelink communication in accordance with atransmission time interval (TTI) may be used. In a non-limiting example,a 3GPP LTE protocol (including but not limited to LTE Release 14) mayuse sidelink communication in accordance with a TTI of one millisecond(msec). In some embodiments, periodic broadcast vehicle-to-vehicle (V2V)communication may be used. In a non-limiting example, a periodicity of100 msec may be used.

In some embodiments, vehicle-to-everything (V2X) communication may beused in accordance with unicast communication, group-cast communication,communication within vehicle platoon and/or other communication. In somecases, communication may be performed in accordance with a latency in arange of 10 to 20 msec, although the scope of embodiments is not limitedin this respect.

In some embodiments, LTE sidelink communication with a shorttransmission time interval (S-TTI) of less than one msec may be used.This TTI may be referred to herein as a “short TTI,” but such referencesare not limiting. Such references may be used for clarity, in somecases. In some scenarios, usage of the short TTI transmission may enablesupport of V2X use cases based at least partly on LTE V2V design andspecification.

In some embodiments, short TTI support in LTE may include several designoptions, some of which are described herein. In some scenarios,coexistence of short TTI communication with LTE R14 resource pools anddesign may be realized. In some embodiments, short TTI operation on adedicated carrier may be used, wherein a short TTI physical structuremay be used. In some cases, for short TTI coexistence with R14 LTE-V2Vcommunication in which same and/or overlapping resource pools are used,various techniques may be used to address potential near-far scenarios.

In some embodiments, enhanced communication using the short TTI (S-TTI)may coexist with legacy LTE V2V communication (with legacy TTI (L-TTI))of 1 msec duration) using the same resource pools as defined in LTE R14.Several scenarios of S-TTI usage with respect to L-TTI operation arepossible, including but not limited to the scenarios described below.These scenarios may be referred to herein as “Scenario 1,”, “Scenario2,”, “Scenario 3,” and “Scenario 4” for clarity, but such references arenot limiting.

In Scenario 1, S-TTI and L-TTI coexistence in a legacy resource pool(LTE R14) may be used, with legacy sidelink control channel (PSCCH,SCI-F1) transmission. In this scenario. S-TTI and L-TTI transmissionsmay share the same resource pool. The enhanced UE 102 (such as R15+) mayutilize S-TTI for communication with other enhanced UEs 102 and maytransmit legacy PSCCH, SCI-Format 1, so that it may be received/decodedby legacy UEs 102 (such as R14) and used for sensing and resourceselection.

In Scenario 2, S-TTI and L-TTI coexistence in a legacy resource pool maybe used, without PSCCH SCI-Format 1 transmission. In this scenario,S-TTI and L-TTI transmissions may share the same resource pool. Theenhanced UE 102 may utilize S-TTI for communication with other enhancedUEs 102, but may not necessarily transmit legacy SCI-F1. In this case,legacy UEs 102 may not be aware of potential S-TTI transmissions, andthus may not be able to take into account these S-TTI transmissionsfollowing legacy sensing and resource selection (e.g. resource exclusionstep). It still may be possible to use energy sensing (S-RSSImeasurements) and/or resource ranking (including but not limited totechniques of an LTE R14 protocol) to avoid collision with S-TTItransmission. However, it still may not be possible to differentiatepriority signaled in SCI-Format1, in some cases.

In Scenario 3, S-TTI and L-TTI transmissions may use different resourcepools, with SCI-F1 transmission enabled. In this scenario, there may notnecessarily be coexistence/compatibility issues when legacy (R14) andenhanced UEs 102 do not share a resource pool, since different pools areused for S-TTI and L-Tri transmissions. From a coexistence point ofview, transmission of SCI-Format 1 by enhanced UEs 102 may notnecessarily be used. However, the SCI-Format 1 transmission could beused by enhanced UEs 102 for entire subframe reservation at least interms of time resources, in some cases.

In Scenario 4, S-TTI and L-Tri transmissions may use different resourcepools, without SCI-F1 transmission. In this scenario, there may notnecessarily be coexistence/compatibility issues. The enhanced UEs 102may benefit from the reduced latency. Half-duplex and in-band emissioneffects may reduce, however a link budget as well, when the S-TTI isutilized.

In some cases, Scenarios 3 and 4 may be considered as scenarios withenhanced UEs 102 in a green field deployment without compatibilityconsiderations. The Scenario 4 may be considered, in some cases, aspromising in terms of improved performance. Scenario 1 and Scenario 2may have multiple technical challenges, including but not limited tochallenges related to control channel design. AGC settling intervaldesign, S-TTI physical structure for PSCCH (sPSCCH) and PSSCH (sPSSCH).One or more of the techniques described herein may address those issues,in some cases.

Some techniques described herein may be related to short TTI controlchannel design, although the scope of embodiments is not limited in thisrespect.

In some embodiments, dedicated control signaling and channels for S-TTImay be defined (for instance, the sPSCCH) in addition to sPSSCH sidelinkshared channel. In some embodiments, the sPSCCH and sPSSCH may followsimilar resource configuration principles as defined for legacy UEs 102and may have similar S-TTI physical structures, although the scope ofembodiments is not limited in this respect. The amount of sPSCCH andsPSSCH subchannels may be reduced in comparison to legacy systems, insome cases. For instance, wideband transmissions may be more typical incase of S-TTI operation, in some cases.

Referring to FIG. 9 , in the example scenario 900, the sPSCCHtransmission 920 may be multiplexed with the sPSSCH transmission 925 inthe frequency domain, during the S-TTI 910. Referring to FIG. 9 , in theexample scenario 950, the sPSCCH transmission 970 may be multiplexedwith the sPSSCH transmission 975 in the time domain. In some cases, thededicated S-TTI 960 may be allocated for multiple sPSCCH transmissions.

In some cases, support of S-TTI in the same resource pool as used bylegacy transmissions may have significant impact on sensing and resourceselection procedures (including but not limited to the procedures oflegacy LTE and/or LTE R14). Such impacts may be different depending onwhether SCI-Format 1 is transmitted or not by enhanced UEs 102 in somecases (including but not limited to Scenario 1 and Scenario 2).

In some embodiments. SCI-Format 1 may be transmitted by enhanced UEs102. In Scenario 1, an enhanced UE 102 may transmit SCI-F1 using L-TTI(for instance, according to the legacy PSCCH physical structure and SCIdesign). In some cases, sPSSCH data may be transmitted in S-TTIallocations. In some cases, additional SCI control signaling may betransmitted inside of S-TTI PSCCH allocation (sPSCCH).

The scenario 1000 in FIG. 10 illustrates a non-limiting example ofmultiplexing of legacy and enhanced PSCCH/PSSCH. The scenario 1000 maybe applicable to Scenario 1, although the scope of embodiments is notlimited in this respect.

In some embodiments, in case of successful SCI-Format 1 reception, thelegacy UE 102 may potentially detect the presence of transmission by anenhanced UE 102 and may thus take this information into account forresource selection. In some cases, one or more of PSSCH-RSRP measurementand S-RSSI measurement may be impacted as part of R14 sensing andresource selection procedure. For the PSSCH-RSRP measurement, if theenhanced UE 102 does not transmit all four DMRSs per subframe, thePSSCH-RSRP measurements may be affected (such as biased and/or other).This measurement may not be available for S-TTI transmissions, in somecases. However, if at least one DMRS is transmitted in S-TTI accordingto the R14 format, the resource exclusion step of resource selectionprocedure may be applied. In some cases, the PSSCH-RSRP measurement maybe degraded. For the S-RSSI measurement, if the enhanced UE 102transmits in the S-TTI portion of the subframe, the S-RSSI measurementmay be affected (such as biased and/or other).

In some embodiments, if sensing-based S-TTI resource selection is used,the following technique may be used for enhanced UEs 102 and/or R15 UEs102. In a non-limiting example, sPSSCH-RSRP and/or S-RSSI measurementsper S-TTI allocation may be used. In some cases, S-TTI resourceallocation may be selected, based at least partly on suchmeasurement(s), for transmission.

In some embodiments, SCI-F1 may not necessarily be transmitted byenhanced UEs 102. The scenario 1050 in FIG. 10 illustrates anon-limiting example of multiplexing of legacy and enhanced PSCCH/PSSCH.The scenario 1050 may be applicable to Scenario 2, although the scope ofembodiments is not limited in this respect.

In Scenario 2, the legacy SCI-F1 is not transmitted by enhanced UE 102.The sPSSCH data may be transmitted in S-TTI allocations, while theadditional SCI control signaling may be also carried inside of S-TTIallocation, in some cases. In some cases, legacy sensing and resourceselection procedure may be affected more significantly. One or more ofthe following may be impacted for legacy sensing and resource selection:priority support, PSSCH-RSRP measurement, S-RSSI measurement and/orother. For the priority support, information about short-TTItransmission priority may not be available to legacy UEs 102 and thustransmission priority of enhanced UEs 102 may not necessarily berespected by legacy sensing and resource selection procedures. On theother hand, enhanced UEs 102 may respect priority of legacy transmissionand therefore there may not be issues from the legacy performanceperspective.

For the PSSCH-RSRP measurement, this measurement may not be availablefor S-TTI transmissions. Therefore the resource exclusion step ofresource selection procedure may not necessarily be properly applied, insome cases.

For the S-RSSI measurement, this measurement may be affected (such asbiased and/or other) similar to the Scenario 1. The ranking and resourceselection procedure may help to exclude high energy resources occupiedby S-TTI transmissions, in some cases.

In some embodiments, transmission of SCI-F1 jointly with short TTI mayreduce the latency benefits that can be provided by short TTI in casesin which enhanced UEs 102 decode SCI-F1 in order to decode sPSSCH.However, the system may be designed in a way that SCI-F1 is transmittedmainly for compatibility considerations to legacy UEs 102, while forenhanced UEs 102, the additional sPSCCH can be defined. In cases inwhich S-TTI control and shared channel are introduced, the latencybenefit of S-TTI transmission may be preserved for V2V communication, insome cases. The scenario 1100 in FIG. 11 illustrates a non-limitingexample of multiplexing of legacy and enhanced PSCCH/PSSCH. The scenario1100 may be related to compatibility and/or latency reductionconsiderations, although the scope of embodiments is not limited in thisrespect. The legacy PSCCH (indicated by 310) may be directed towardlegacy UEs 102 for compatibility reasons, in some cases. The sPSCCH(indicated by 315) may be directed toward enhanced UEs 102 for latencyreduction, in some cases.

In some cases, AGC dynamic range, implementation overhead and/or otherissues may be considered. In a non-limiting example, a near-far problemmay be related to AGC dynamic range. The multiplexing of S-TTI and L-TTItransmissions in the same subframe can have significant impact on legacyUE 102 demodulation performance. For instance, when legacy UEs 102receive data from the distant legacy transmitters and nearby enhancedUEs 102 trigger S-TTI transmission starting in the middle of a subframe,a significant near far issue may happen for legacy UE 102 reception. Thelegacy UE 102 may not be expected to adjust AGC at every symbol oraccording to S-TTI granularity in time. This issue may lead tosignificant non-linear distortions and may potentially affect receptionof legacy UEs 102 and/or R14 UEs 102.

In some embodiments, the enhanced UE 102 may use one or more of thefollowing transmission options. Such options may mitigate dynamic rangeissues for legacy UEs 102, in some cases. In a first option, theenhanced UE 102 may use multiple S-TTIs within subframe. This may reducethe latency and/or increase reliability, in some cases. Multipleenhanced UEs 102 may be multiplexed in the frequency domain, in somecases. In this case, the legacy UE 102 may use a first symbol in thesub-frame to settle its AGC parameters according to legacy behavior. Thescenario 1130 in FIG. 11 illustrates a non-limiting example of the firstoption.

In a second option, the enhanced UE 102 may transmit a signal in thefirst symbol of a sub-frame. In some cases, this may enable legacy UEs102 to settle their AGC according to a maximum expected level ofreceived power range within a subframe. The scenario 1160 in FIG. 11illustrates a non-limiting example of the first option. The AGC trainingsymbol (indicated by 1175) is transmitted during the first symbol of thesub-frame 1165.

In some embodiments, a dedicated region within each S-TTI may bedefined. In some cases, this may enable enhanced UEs 102 to preciselysettle AGC before each S-TTI reception.

In some embodiments, legacy UEs 102 and/or R14 UEs 102 may assume onesymbol for AGC settling time. If the same assumption is kept in case ofS-TTI, then depending on the number of S-TTIs within subframe, the AGCimplementation overhead may grow substantially. For legacy UE 102. AGCimplementation overhead may be one symbol per subframe. For enhanced UEs102, the AGC implementation overhead may increase to the amount ofS-TTIs per sub-frame. One or more of the following techniques may beused to reduce the AGC overhead. In a first technique, a faster AGCconvergence may be used. An AGC convergence time within a CP durationmay be desirable, for instance, for Enhanced UEs 102. In a secondtechnique, the first symbol of the sub-frame may be used for AGCtraining. UEs 102 that are planning to occupy the S-TTI portion of thesub-frame may transmit additional signal for AGC settling at thebeginning of each subframe (for instance, the first symbol of thesubframe may be an AGC training symbol) independently from S-TTIallocation within the sub-frame. This approach may enable AGC operationat the subframe rate, may reduce the AGC implementation overhead and/ormay result in AGC behavior consistent with legacy UE 102 behavior.

In some embodiments, one or more of the following signals may be usedfor AGC training. In a non-limiting example, a dedicated preamble orreference signal may be used. Some or all UEs 102 may transmit the samesignal. The signal may be predefined in a specification and/orconfigured by network/eNBs 104, in some cases. In another non-limitingexample, demodulation reference signals (DM-RSs) may be used. Each UE102 may randomly select a particular sequence from a predefined set ofDM-RS sequences. In another non-limiting example, sPSSCH/sPSCCH data maybe used. Resources used for AGC settling may be used for datatransmission. In that case, the data symbol may be used as an AGCtraining sequence. In some embodiments, the sequence may or may not bepunctured at the receiver depending on convergence time. In anothernon-limiting example, a copy of the data symbol from sPSSCH/sPSCCH maybe used. In this case, symbols used for AGC settling may or may not becombined for data reception, depending on AGC convergence time for agiven subframe. The copy of the data symbol from S-TTI allocation may beused as an AGC training symbol.

Various options for the short TTI are presented below. Embodiments arenot limited to these options. The options include slot and sub-slotlevel S-TTI physical structures of different sizes for sPSCCH and sPSSCHchannels.

A set of basic S-TTI patterns may assume a fixed number of symbols foreach S-TTI pattern. The S-TTI patterns may be constructed fromdemodulation reference signals (DM-RS) and data symbols, which may carryinformation of any defined sidelink channel (including but not limitedto a control channel (PSCCH), shared channel (PSSCH), broadcast channel(PSBCH), discovery channel (PSDCH) and/or other).

Non-limiting examples of S-TTI patterns are shown in FIGS. 12 and 13 .Embodiments are not limited to the number of DMRS symbols, the number ofPSSCH symbols, the arrangements of DMRS symbols and PSSCH symbols, theordering of DMRS symbols and PSSCH symbols or to other aspects of theexamples. The examples shown in FIGS. 12 and 13 are not exhaustive.Additional patterns similar to those shown may be used, in someembodiments. In some embodiments, one or multiple data symbols from anybasic pattern may be punctured. In some embodiments, one or multipledata symbols from any basic pattern may be used for transmission ofother signals (including but not limited to AGC training signal,ranging/positioning reference signals and/or other). In someembodiments, symmetric S-TTI patterns may be considered as candidatesfor LTE S-TTI sidelink physical structures. In a non-limiting example,such structures may include ranges of symbols from 1 to 7. S-TTIstructures for larger number of symbols may be based on aggregation ofS-TTI patterns, including but not limited to the example patterns shownin FIGS. 12 and 13 .

It should be noted that in the examples shown and in other embodiments,one or more data symbols may also include resource elements (REs)occupied by demodulation reference signals (DM-RS RE). For instance, asshown in 1200, the PSSCH 1202 may include DMRS 1206 and data signals1204. This arrangement may be extended to the symbols in other examplesof FIGS. 12 and 13 , although the scope of embodiments is not limited inthis respect. The example 1200 may be a basic S-TTI pattern of sizeequal to one. Basic S-TTI patterns for the lengths from 2 to 7 are shownin Error! Reference source not found. The basic set of S-TTI patternscould further be extended using concatenation/combination of one ormultiple basic S-TTI patterns.

In the example 1210 in FIG. 12 , two patterns 1211 and 1215 are shown.The pattern 1211 includes a PSSCH 1212 followed by DMRS 1213. Thepattern 1215 includes DMRS 1216 followed by the PSSCH 1217. Also in FIG.12 , three example patterns 1221, 1222, and 1223 are shown. Each ofthose patterns includes three symbols (one DMRS symbol and two PSSCHsymbols). Various orderings of the DMRS symbol and PSCCH symbols areshown.

In FIG. 13 , four example patterns 1300, 1301, 1302, and 1303 are shown.Each of those patterns includes four symbols. Patterns 1300 and 1301include one DMRS symbol and three PSSCH symbols. Patterns 1302 and 1303include two DMRS symbols and two PSSCH symbols. In FIG. 13 , fourexample patterns 1310, 1311, 1312, and 1313 are shown. Each of thosepatterns includes five symbols. Patterns 1310 and 1311 include one DMRSsymbol and four PSSCH symbols. Patterns 1312 and 1313 include two DMRSsymbols and three PSSCH symbols. Patterns that include three or moreDMRS symbols are also possible.

In some embodiments, patterns of more than five symbols are possible.Various numbers of DMRS symbols and PSSCH symbols may be used. Variousordering/arrangements of the DMRS and PSSCH symbols may be used.

In some embodiments, an S-TTI structure of size m may include k AGCsettling symbols. It may be constructed using basic S-TTI structure ofsize m-k. For example, an S-TTI of size four with one AGC settlingsymbol may be constructed using basic S-TTI pattern of size three andone AGC symbol appended to the beginning of the basic S-TTI pattern. Anexample of such is shown in FIG. 14 , in which the unit 1406 is based onthe AGC symbol 1402 prepended to the unit 1404. Embodiments are notlimited to the number, arrangement or other aspects of the DMRS andPSSCH shown in FIG. 14 . For instance, units of size other than three(as in 1404) may be used.

In some embodiments, an S-TTI pattern with reserved/excluded symbolsconstruction may be used. In a non-limiting example, an S-TTI pattern ofsize m with k excluded/reserved symbols may be constructed from L basicS-TTI patterns in accordance with a relationship in which a summation ofk and pattern sizes of the L basic S-TTI patterns is equal to m. Forinstance, the relationship below or a similar relationship may be used.

${k + {\sum\limits_{i = 1}^{L}{{pattern}\_{size}}_{i}}} = m$

In some embodiments, an LTE frame structure with a sidelink S-TTI may beused. Based on a set of S-TTI structures and procedures of S-TTIpatterns construction, the LTE sidelink frame structure of the followingtwo types may be constructed. In a non-limiting example, the subframestructure may be aligned with legacy (including but not limited to LTER14) sidelink subframe structure. The S-TTI design, which results insubframe structure, may be aligned with the legacy subframe. This may beused to realize benefits of legacy SCI-F1 usage, in some cases. In thiscase, legacy UEs 102 may perform AGC settling and PSSCH-RSRPmeasurements using legacy procedures.

In another non-limiting example, a different frame structure with aspecific subframe structure may be used. In some embodiments, a subframestructure may differ from a legacy (such as LTE R14 and/or other)subframe structure. While the S-TTI structure may be optimized forenhanced UE 102 reception and/or R15 UE 102 reception, the legacy LE 102performance may be degraded due to improper PSSCH-RSRP and S-RSSImeasurements, in some cases.

In some embodiments, an S-TTI sub-frame structure may be aligned withlegacy (such as LTE R14 and/or other) PSSCH/PSCCH sub-frame structure.In some embodiments, legacy DMRS structure may include four DMRSs persub-frame. Assuming that DMRS position and waveform are not changed (toreduce impact on legacy sensing and resource selection procedure), theS-TTI configuration options may be limited, in some cases. In someembodiments, the S-TTI may have either one or two DMRS symbols,resulting in slot based S-TTI and sub-slot based S-TTI physicalstructures.

In some embodiments, in legacy operation, a last symbol (such as a finalsymbol) of a sidelink subframe may be punctured. In some embodiments,for S-TTI based operation, the puncturing described above may notnecessarily be used. In addition, in some cases of S-TTI, the lastsymbol of the subframe may be used for S-TTI transmission. It may beassumed, in some cases, that there is enough time to perform AGC andTX/RX turnaround within one symbol. Otherwise, the reception ofsubsequent S-TTI may be skipped.

In some embodiments, slot and sub-slot based S-TTI structures may beused. In cases of slot level TTI, two DMRSs may be present per S-TTIwhich spans one slot. In cases of sub-slot level TTI, one DMRS may beused per S-TTI. The amount of symbols per S-TTI may depend on one ormore assumptions of AGC operation for enhanced UEs 102 and/or R15 UEs102. In a non-limiting example, one symbol for AGC settling within theS-TTI may be used. In another non-limiting example, a dedicated AGCsymbol may be used at the first symbol of the subframe. This may beconsidered a “fast AGC” in some cases, although the scope of embodimentsis not limited in this respect.

Non-limiting example sub-frame constructions are shown in FIGS. 14-17 .The examples are not exhaustive. In some embodiments, a structure may bebased on one or more of the structures shown in FIGS. 14-17 . In someembodiments, a structure may be similar to one or more of the structuresshown in FIGS. 14-17 . Embodiments are not limited to the number, type,arrangement and/or other aspects of the symbols shown.

In some embodiments, a GAP symbol may be either occupied by S-TTI withincreased number of symbols or allocated for one symbol S-TTI that maybe used for transmission of fast responses or acknowledgements.

In some embodiments, structures may be aligned with legacy structures.For instance, a structure may be aligned with a legacy LTE (includingbut not limited to LTE R14) sidelink PSSCH/PSCCH subframe structure.Examples are shown in FIGS. 14 and 15 . The structure 1410 is inaccordance with a sub-frame granularity and further in accordance withan AGC settling within one symbol duration. The structure 1420 is inaccordance with a sub-frame granularity and further in accordance withan AGC settling within a normal cyclic prefix (CP). The structure 1430is in accordance with a sub-frame granularity and further in accordancewith an AGC settling at the first symbol of the sub-frame. Thisstructure includes the AGC symbol 1432.

The structure 1510 is in accordance with a slot granularity (includingbut not limited to 6 or 7 symbols) and further in accordance with an AGCsettling within one symbol duration. The structure 1520 is in accordancewith a slot granularity and further in accordance with an AGC settlingwithin a normal cyclic prefix (CP). The structure 1530 is in accordancewith a slot granularity and further in accordance with an AGC settlingat the first symbol of the sub-frame. This structure includes the AGCsymbol 1532.

The structure 1540 is in accordance with a sub-slot granularity(including but not limited to 3 or 4 symbols) and further in accordancewith an AGC settling within one symbol duration. The structure 1550 isin accordance with a sub-slot granularity and further in accordance withan AGC settling within a normal cyclic prefix (CP). The structure 1560is in accordance with a sub-slot granularity and further in accordancewith an AGC settling at the first symbol of the sub-frame. Thisstructure includes the AGC symbol 1562.

In some embodiments, including but not limited to cases of arbitraryframe structure, the S-TIs boundaries may not necessarily be alignedwith legacy LTE subframe boundaries.

In some embodiments, the S-TTI may be aligned with legacy LTE subframeboundaries. A subframe may include an integer number of S-TTIs.Depending on subframe design and AGC settling time assumptions, thesubframe may include one or more of: one or more S-TIs with dedicatedAGC settling time within each S-TTI; one or more S-TTIs withoutdedicated AGC settling time interval; shared AGC settling time intervaland S-TTIs without dedicated AGC settling time; and/or other. Inaddition, the subframe may also include one or more reserved symbols.For instance, such reserved symbol(s) may be used for TX/RX switching,additional reference signal transmission and/or other.

Non-limiting examples of subframe structure construction for subframewith Normal Cyclic Prefix type are shown in FIG. 16 . Similar structuresmay also be constructed for subframes with Extended Cyclic Prefix. Theexample structures in FIG. 16 may be constructed without legacysub-frame structure preservation, in some cases. The structure 1610 isin accordance with a slot granularity (including but not limited to 6 or7 symbols) and further in accordance with an AGC settling within onesymbol duration. The structure 1620 is in accordance with a slotgranularity and further in accordance with an AGC settling within a CP.The structure 1630 is in accordance with a slot granularity and furtherin accordance with an AGC settling at the first symbol of the sub-frame.This structure includes the AGC symbol 1632. The structure 1640 is inaccordance with a sub-slot granularity (including but not limited to 3,4 or 5 symbols) and further in accordance with an AGC settling withinone symbol duration. The structure 1650 is in accordance with a slotgranularity and further in accordance with an AGC settling within a CP.The structure 1660 is in accordance with a sub-slot granularity andfurther in accordance with an AGC settling at the first symbol of thesub-frame. This structure includes the AGC symbol 1662.

In some embodiments, S-TTI design without legacy subframe boundariesalignment may be used. In some embodiments. S-TTIs may follow one by onewithout alignment with legacy subframes boundaries. Similar to othercases described herein, each S-TTI may include a dedicated AGC symbol.Otherwise, the shared AGC symbol may be repeated with a predefinedperiod. Examples of continuous S-TTI design for three different TTIsizes and three different frame structures designed for different AGCoperation modes is shown in FIG. 17 . The structure 1710 is inaccordance with a granularity of a unit that includes a number ofsymbols and further in accordance with an AGC settling within one symbolduration. The examples in FIG. 17 illustrate constructions in accordancewith a slot granularity of three symbols, but any suitable number ofsymbols may be used. The structure 1720 is in accordance with agranularity of a unit that includes three symbols and further inaccordance with an AGC settling within a CP. The structure 1730 is inaccordance with a granularity of a unit that includes three symbols andfurther in accordance with an AGC settling at the first symbol of thesub-frame. This structure includes the AGC symbol 1732.

In some embodiments, the S-TTI structure may be used to broadcast data.In some cases, there may also be some advantages for group-cast andunicast transmissions when fast acknowledgement or response is needed.In some cases, the legacy SCI-F1 transmission may be used to reserveresources for S-TTI transmissions (including but not limited to fastresponses). It should be noted that a similar mechanism may be enabledwith S-TTI control signaling, but may be incompatible with legacy UEs102 and may require finer timescale for resource selection.

For instance, in case of two TTI transmissions, the UE 102 supportingS-TTI Tx/Rx may use a first TTI for transmission and may follow thelegacy procedure (for instance, usage of legacy PSCCH and PSSCH). The UE102 may reserve the second TTI and may use it for reception to collectresponses from a group of vehicles in S-TTI transmission format.Alternatively, the UE 102 may use legacy PSCCH transmission incombination with the sPSCCH and sPSSCH to reserve resources for fastunicast responses from a group of UEs 102. Examples 1800, 1850 shown inFIG. 18 illustrate such concepts.

In some embodiments, the sPSCCH channel may be used to transmit theresource allocation grants for sPSSCH transmissions. Example 1900 inFIG. 19 illustrates this concept.

In some embodiments, a method of sidelink communication for V2V(vehicle-to-vehicle) communication may include one or more of:configuration of sidelink Short Transmission Time Intervals (S-TTIs)used for communication, configuration of S-TTI based physical sidelinkcontrol channel (sPSCCH) and S-TTI physical sidelink shared channel(sPSSCH); configuration of FDM/TDM multiplexing for sPSCCH and sPSSCHtransmission; sidelink communication using S-TTI and L-TTI transmissionformats within a same set of resources (resource pools); sidelinkcommunication using S-TTI transmission formats on dedicated set ofresources; measurements of S-RSSI and PSCCH/PSSCH RSRP based on S-TTIphysical structure; sensing and resource selection, for transmission ofsidelink shared and control channel based on either S-TTI or L-TTIresource allocations; transmission of two SCI-Formats, one intended tolegacy (such as LTE R14) terminals and other intended to enhanced (suchas R15) terminals; transmission of SCI to reserve S-TTI resources fortransmission by other UEs 102, and/or other.

In some embodiments, the sidelink S-TTI may comprise 1, 2, 3, 4, 5, 6,or 7 symbols including DMRS, and sidelink control or shared channeltransmission. The DMRS signal allocation within S-TTI may be predefinedaccording to one of the basic patterns. In some embodiments, sPSCCHand/or sPSSCH physical structures may be defined based on S-TTIstructure and transmitted within subframe duration.

In some embodiments, sidelink communication may use S-TTI and L-TTItransmission formats of PSCCH and PSSCH within the same set of resources(resource pools). In some embodiments, one or multiple UEs 102 may useL-TTI transmission format for communication (PSCCH/PSSCH). In someembodiments, one or multiple UEs 102 may use S-TTI transmission formatfor communication (sPSCCH/sPSSCH). In some embodiments, one or multipleUEs 102 may use S-TTI to transmit two SCI formats, one for legacy UEs102 (PSSCH) and another for enhanced UEs 102 (PSCCH or sPSCCH). This mayenable seamless coexistence within same set of resources, in some cases.In some embodiments, one or multiple UEs 102 may use S-TTI to transmitone or more AGC training symbols at the beginning of each subframe toenable adjustment of AGC for legacy UEs 102. The AGC training symbol(s)may be dedicated AGC signal(s), DMRS, data symbols and/or other. In someembodiments, one or multiple UEs 102 supporting S-TTI may operate usingfast AGC, by adjusting AGC at each S-TTI occurrence in time, withincyclic prefix duration.

In some embodiments, S-TTI transmission may be permitted on dedicatedresources comprising sPSCCH/sPSSCH resource pools or S-TTI componentcarriers. In some embodiments, S-RSSI, PSCCH/PSSCH RSRP measurements maybe defined for S-TTI structure or configured time granularity. In someembodiments, S-RSSI. PSCCH/PSSCH RSRP measurements defined for S-TTIstructure may be used for S-TTI resource selection with finer timegranularity. In some embodiments, the UE 102 may select resources fortransmission by other UEs 102. In some embodiments, the UE 102 mayinform other UEs 102 about S-TTI resources reserved for theirtransmission using either SC format for legacy UEs 102 and/or enhancedUEs 102.

In some embodiments, the S-TTI may comprise one or more of: a PSCCHsignal, a PSSCH signal, an AGC training signal, one or more DMRS and/orother. In some embodiments, the S-TTI structure may be based on one ormore basic patterns. In some embodiments, one or more S-TTIs may followconsecutively in time. In some embodiments, an LTE subframe may comprisean integer number of S-TTIs. In some embodiments, multiple LTE subframesmay comprise the same number of S-TTIs. In some embodiments. DMRStransmitted in S-TTIs may be at the same symbols as in an LTE subframe.

In some embodiments, including but not limited to embodiments thatinclude operation in accordance with a 3GPP LTE Release 14 (LTE R14)specification, vehicle-to-vehicle (V2V) communication may be supported.In some cases, periodicities of greater than 100 msec may be used. Insome cases, latency of 100 msec or less may be used. In someembodiments, reduced latency (such as 20 msec or other value) may beused. Such a reduced latency may provide challenges in some use cases,including but not limited to use cases which are based on shorttransmission period and low latency requirement. Accordingly, techniquesto enable LTE V2V communication for reduced latency may be beneficial,in some cases. In some embodiments, vehicle-to-everything (V2X) systemsmay operate in accordance with latencies much smaller than 100 msec.

In some embodiments, techniques may be used to support communicationwith a relatively short packet generation period and/or relatively lowlatency. In some embodiments, enhancements may be applied to legacy(including but not limited to LTE R14) V2V sensing and resourceselection procedure to support transmission with the reduced latency.For instance, enhancements to sensing window and resource selectionwindow as well as new UE 102 behavior may reduce latency of LTE V2Vcommunication, in some cases.

In some embodiments, including but not limited to embodiments thatinclude operation in accordance with legacy LTE and/or LTE R14, whenrequested by higher layers in subframe n, the UE 102 may determine theset of resources for PSCCH/PSSCH transmission. The UE 102 may assumethat any resource within the time interval └n+T1, n+T2┘ corresponds toone candidate single-subframe resource Selections of T1 and T2 may be upto UE 102 implementations under T1≤4 and 20≤T2≤100 restrictions, in somecases. The selection of T2 by the UE 102 may also fulfill a targetlatency. For resource selection, the UE 102 may monitor subframes└n-1000, n-999 . . . . , n-1┘ except for those in which itstransmissions occur. The UE 102 may perform the resource selectionprocedure based on PSCCH decoding and/or RSRP, S-RSSI measurements inthese subframes. A non-limiting example of LTE legacy V2V resourceselection is shown in FIG. 20 .

In some embodiments, including but not limited to embodiments thatinclude operation in accordance with legacy LTE and/or LTE R14, amaximum time between packet arrival at L1 and resource selected fortransmission may be determined by the value of T2, which may vary fromT2 min=20 to T2max=100 and may be subject to latency constraint. Basedon a legacy subframe duration of one msec, this approach may enable 20msec latency and transmission period for V2V communication, in somecases.

In order to further reduce the maximum time between packet arrival at L1and resource selected for transmission, the min and max value of T2 maybe further reduced in a non-limiting example, one or more of thefollowing may be used: T2 min=T1; T2max=10 msec; 4≤T1≤T2≤10.

In a non-limiting example, latencies may vary from 3 msec to 100 msecand specific T2 value may be configured by higher layers, in some usecases. In another non-limiting example, latencies may vary from 10 msecto 20 msec, in some use cases. In some cases, latency reduction below 20msec for resource selection may lead to an increased probability ofcollision if multiple UEs 102 operate with low latency, including butnot limited to latencies of 20 msec or below. This may be due to one ormore factors, such as a lack of resources in selection window,half-duplex issues and/or other. In some cases, if latencies such as 20msec, 10 msec or similar are expected, it may not necessarily bebeneficial to mix such transmissions with the transmissions utilizingtransmission intervals greater than 100 msec.

In some embodiments, restriction of the resource reservation intervalsper pool configuration may be used. However, a sensing window of onesecond may be used, in some cases. This window size may be independentof pool configuration and the UE 102 may be expected to keep a selectedresource for at least half a second in time and thus may consistentlycollide until the next resource reselection. Accordingly, one or moretechniques may be applied to further reduce latency and/or resourcereservation period.

In a non-limiting example technique that may be applied to furtherreduce latency and/or resource reservation period, a pool-specificreference reservation period may be used. For each resource pool thereference reservation period may be signaled. This value may signify atypical expected generation period of the packets transmitted in suchpool, in some cases. In this case, parameters for sensing, resourceselection and congestion control may be determined based on thereference reservation period value, a transmission time interval value(T_(TTI)) and/or other.

In a non-limiting example, a legacy LTE reference resource reservationperiod may be P_(Basic)=100, and a value of T_(TTI)=SubframeDuration=1msec may be used. In this case, the main sensing, resource selection andcongestion control parameters may be derived as follows: sensing windowduration: T_(SensWindow)=10*P_(Reference) resource selection windowT_(2Max)=P_(Reference), resource reselection counter range:Counter_(Reset)=1500, 600, . . . , 1500) P_(Tx) forP_(Tx)<P_(Reference); maximum number of reservations of other UE withinRx UE resource (re)-selection window: N_(resv)=P_(Reference)/P_(Tx), forP_(Tx)<P_(Reference); P_(step_nonTDD)=P_(Reference); other Pstep values(which may be determined taking into account DL/UL configuration),congestion control Channel Busy Ratio measurement duration:T_(CBR)=P_(Reference); and/or other. A non-limiting example in FIG. 21shown LTE sensing and resource selection parameters derivation fromreference resource reservation period value.

In another non-limiting example technique that may be applied to furtherreduce latency and/or resource reservation period, pools restricted tosmall periods may be used (for instance, restricted to low latencytransmissions). This functionality may be enabled by the extension ofthe list of valid values allowed for LTE R14 parameter“restrictResourceReservarionPeriod” assignment and adding lower valuesto this field. Embodiments are not limited to usage of this parameter,however, as other parameters and/or messages may be used in someembodiments.

In another non-limiting example technique that may be applied to furtherreduce latency and/or resource reservation period, a reduced sensingwindow may be used. In a legacy system (including but not limited to LTER14), a sensing window of one second may be used independently ofperiodicity and resource reservation interval used for transmission. Thesensing window duration may be shortened for some cases in which onlylow latency transmission (small resource reservation periods) areconfigured per resource pool.

In another non-limiting example technique that may be applied to furtherreduce latency and/or resource reservation period, a reduced resource(re)-selection time may be used. The resource (re)-selection time may bereduced by decreasing the number of TBs transmitted before the resourcereselection. For instance, the times may be reduced from [25, 75] for 20msec in LTE R14 to [5 15] msec if a small resource reservation period isconfigured per pool. The resource reselection counter values may beconfigurable per pool.

In another non-limiting example technique that may be applied to furtherreduce latency and/or resource reservation period, a reduced resource(re)-selection window may be used. The resource (re)-selection windowmay be bounded, in some cases, by a minimum T₂ value equal to 20. If thevalue of T₂ is reduced further, the latency can be decreasedaccordingly. Therefore values such as 5 or 10 may be used aspre-configuration values or T2 values can be configured by higher layerswithin predefined bounds, in some embodiments.

In another non-limiting example technique that may be applied to furtherreduce latency and/or resource reservation period, multiple transmissionprocesses may be used. The utilization of multiple transmissionprocesses with resource selection windows shifted in time may beutilized to reduce the overall transmission latency. In some cases, thisapproach may reduce latency in an average statistical sense. In somecases, this approach may be applied in combination with other principlesto comply with strict latency targets.

In another non-limiting example technique that may be applied to furtherreduce latency and/or resource reservation period, a “first in time”candidate resource selection may be used. In some embodiments, includingbut not limited to embodiments that include usage in accordance with LTER 14 and/or other legacy protocol, a resource for transmission may berandomly selected from the set of candidate resources within a resourceselection window. Instead of using random resource selection, it may bepossible to select the first resource in time among set of candidateresources and thus reduce latency in an average sense.

In another non-limiting example technique that may be applied to furtherreduce latency and/or resource reservation period, a number of remainingtransmissions may be signaled. This information may be used by UEs 102performing resource reselection to predict resource occupation andproperly select resources. A non-limiting example of LTE sensing andresource selection parameters derivation from basic resource reservationperiod value is shown in FIG. 22 . The UE 102 may be permitted to selecta resource currently occupied by another UE 102 if it is informed thatthe resource will be released by the other UE 102 within the reselectionwindow. If probabilistic resource reselection mechanism is enabled, theUE 102 that transmits the data may check in advance whether resourcereselection occurs and may signal the proper value. In order to minimizethe signaling overhead, the maximum value may be signaled if a number ofremaining transmissions exceeds a predefined threshold. This techniquemay not necessarily affect latency, but may improve the overall sensingand resource selection performance in some cases.

In another non-limiting example technique that may be applied to furtherreduce latency and/or resource reservation period, a number of reservedtransmissions may be signaled. This information and/or a number ofremaining transmissions may be used to determine one or more of: when aresource reservation started; when the resource reservation is expectedto end. This information may be beneficial to compensate estimation ofthe received power at the specific resource if the UE 102 has areselected resource. The power received from the specific signal sourcemay be subtracted from the total received power if the receiver is awarethat the transmitter has already released the resource.

In another non-limiting example technique that may be applied to furtherreduce latency and/or resource reservation period, a short reservationperiod signaling in SCI may be used. The resource reservation period maybe signaled in SCI using a ‘Resource reservation’ field. In someembodiments, other techniques for resource reservation signaling in SCImay be used. In a non-limiting example of a technique for resourcereservation signaling in SCI, a list of reservation periods may beextended. New reservation periods may be included into the list ofsupported reservation periods. In this case, the enhanced UEs 102 may beable to correctly decode this field in SCI. The legacy UEs 102 may notbe able to detect the resource reservation period correctly, which maynegatively affect their resource selection decisions. Accordingly,coexistence of R14 and R15 UEs in the same resource pool may beproblematic.

In another non-limiting example of a technique for resource reservationsignaling in SCI, a field to scale configured resource reservation valuemay be used. A ‘ResvPeriodScale’ field (which may be referred to as “M”below for clarity) or similar may signal a multiplier to be usedtogether with signaled legacy resource reservation period to obtain theactual resource reservation period. The reservation period and scalefactor may be selected in accordance with different values for theparameter M. Two non-limiting examples for M are given below. In a firstexample, M may be an arbitrary value. In this case the enhanced UEs 102may be able determine resource reservation period correctly. However,the legacy UEs 102 may use the wrong information about resourcereservation which may degrade their resource selection performance. In asecond example, M may be based on 1/N wherein N may be a downscalefactor represented with an integer value. In some cases, the coexistenceof enhanced UE PSCCH signaling with legacy UE 102 reception behavior maybe achieved. The legacy UE 102 may interpret transmission from a singleenhanced UE 102 with short period transmission as N differenttransmissions from different UEs 102 and may take them into accountduring sensing and resource selection.

A non-limiting example of small period resource signaling compatiblewith legacy UE sensing and resource selection procedures is shown inFIG. 23 . As it is shown in FIG. 23 , the Enhanced UE 102 transmissionwith short transmission period P_(Tx) 2315 is transmitted with two SCIprocesses 2320, each with signaled legacy reservation period P_(Rsvp),2342 but actual transmission period two times less.

In some embodiments, in addition to the resource reselection procedurebased on processing of long sensing window, the short term sensing atthe beginning of each subframe (for instance the first symbol of thesub-frame) may be used. The UE 102 may be permitted to transmit in aspecific subframe if short term sensing results indicate that receivedpower in a whole symbol or particular sub-channel of the first symbol isbelow a threshold and/or the received power estimate of the selectedcandidate resource.

In some embodiments, a congestion control mechanism may be based on oneor more metrics, including but not limited to those described below. Ina first example metric, a channel busy ratio (CBR) measured in subframen may be defined for the PSSCH. PSCCH and/or other. For the PSSCH, theportion of sub-channels in the resource pool for which an S-RSSImeasured by the UE 102 exceeds a threshold sensed over a range ofsubframes. A non-limiting example range includes subframes └n-100, n-1┘.Ranges of other sizes may be used. For the PSCCH, in a pool that isconfigured such that PSCCH may be transmitted with its correspondingPSSCH in non-adjacent resource blocks, the portion of the resources ofthe PSCCH pool whose S-RSSI measured by the UE exceed a threshold sensedover a range of subframes may be used. A non-limiting example rangeincludes subframes [n-100, n-1]. Ranges of other sizes may be used. Itmay be assumed, in some cases, that the PSCCH pool includes resourceswith a size of two consecutive PRB pairs in the frequency domain.

In a second example metric, a channel occupancy ratio (CR) evaluated atsubframe n may be defined as a total number of sub-channels used for itstransmissions in subframes [n−a, n−I] and granted in subframes [n, n+b]divided by the total number of configured sub-channels in thetransmission pool over [n−a, n+b]. In some embodiments, the parameter amay be a positive integer and b may be a non-negative integer. In anon-limiting example, a and b may be determined by UE implementationwith a+b+1=1000, a>=500. In addition, b may be selected such that (n+b)does not exceed the last transmission opportunity of the grant for thecurrent transmission, in some embodiments.

In some embodiments, a congestion control design may be based onmanagement of the traffic with 100 msec latency and packet generationperiod ≥100 msec. In a non-limiting example, the CBR measurementduration may be selected as 100 msec and the CR estimation interval maybe equal to one second.

In some embodiments, if the packet transmission period is significantlyshorter than 100 msec, the correlated CBR measurements that areperformed before each transmission may be observed. To overcome thisissue, the reduced CBR measurement duration for short periodcommunication may be used. For instance, for 20 msec packet generationperiod, T_(CBR)=20 msec or below (for instance 10 msec) may be used.

In some embodiments, if the short period transmissions are configured ina resource pool, a duration of one second may be excessive for CRestimation. For that case, the CR estimation duration may also bereduced proportionally, in some cases.

In some embodiments, a method of sidelink vehicle-to-vehicle (V2V)communication may be performed. In some cases, low latency and shorttransmission period may be used and/or realized, although the scope ofembodiments is not limited in this respect. The method may comprise oneor more of: configuration of resource pool sensing window, resourceselection window and congestion measurement parameters; selection, by aUE 102, of resources for low latency/short period transmission withmultiple resource selection windows, signaling, by the UE 102, of one ormore resource reservation parameters in SCI. In some embodiments, thereference resource reservation period may be configured per poolrepresenting the dominant transmission period. In some embodiments,resource selection, sensing and congestion control parameters may bederived from the configured reference resource reservation period. Insome embodiments, the pool may be configured with restriction on UE 102resource reservation period. For instance, values of 20, 10 and/or 5msec may be used.

In some embodiments, a sensing window duration may be configured perresource pool. In some embodiments, the sensing window duration maydepend on permitted resource reservation periods (or reference resourcereservation period). In some embodiments, the sensing window durationmay be smaller than one second in duration. In some embodiments, aminimum duration of the resource selection window measured from resourcereselection trigger may be less than 20 msec (for instance, 5 or 10 msecor below and/or values configured by higher layers).

In some embodiments, multiple “shifted in time” resource selectionwindows may be configured. In some embodiments, the largest time shiftbetween resource selection windows may be not larger than a packetgeneration period divided by a number. In some embodiments, the resourcefrom resource selection window with smaller time distance measured fromresource reselection trigger instance may be selected with higherpriority. In some embodiments, a first in time resource may be selectedfor transmission among candidate set of resources. In some embodiments,a number of remaining reserved transmissions may be signaled within SCIforgiven resource reservation process. In some embodiments, a totalnumber of reserved transmissions may be signaled within SCI. In someembodiments, the short reservation period may be signaled within SCI.

In some embodiments, the signaling may be implemented with a resourcereservation value signaled within SCI. In some embodiments, thesignaling may be implemented in a backward compatible way withadditional field in SCI representing the scale applied to a legacy(including but not limited to LTE R14) reservation period. Theadditional field may be used to calculate actual reservation period inorder to make it compatible with legacy sensing and resource selectionbehavior.

In some embodiments, a scale factor signaled in SCI may be an arbitraryvalue. In some embodiments, a scale factor signaled in SCI may representa number to be used for a quotient (such as of the form 1/N).

In some embodiments, a reduced channel busy ratio measurement durationmay be configured per pool. In some embodiments, a channel busy ratiomeasurement duration may be less than 1K00 msec. In some embodiments, areduced (such as less than one second or other value) channel occupancyratio estimation interval may be configured per pool or derived from theactual sensing window duration. In some embodiments, the channeloccupancy ratio estimation interval may be less than one second. In someembodiments, the channel occupancy ratio estimation interval may bederived from a sensing window duration.

In Example 1, an apparatus of a User Equipment (UE) may comprise memory.The apparatus may further comprise processing circuitry. The processingcircuitry may be configured to select, from a plurality of shorttransmission time intervals (TTIs), a short TTI for a vehicle-to-vehicle(V2V) sidelink transmission by the UE. The short TTIs may occur within alegacy TTI. The short TTIs may be allocated for V2V sidelinktransmissions by non-legacy UEs and the legacy TTI may be allocated forV2V sidelink transmissions by legacy UEs. The processing circuitry maybe further configured to encode, for transmission in accordance with thelegacy TTI, a legacy physical sidelink control channel (PSCCH) toindicate, to legacy UEs, the V2V sidelink transmission by the UE. Theprocessing circuitry may be further configured to encode, fortransmission in accordance with the selected short TTI, a short PSCCH(sPSCCH) to indicate, to non-legacy UEs, the V2V sidelink transmissionby the UE. The memory may be configured to store information thatidentifies the selected short TTI.

In Example 2, the subject matter of Example 1, wherein the processingcircuitry may be further configured to encode, for the V2V sidelinktransmission by the UE, a short physical sidelink shared channel(sPSSCH) based on a block of data bits. The sPSSCH may be encoded fortransmission in accordance with the selected short TTI. The sPSSCH andthe sPSCCH may be encoded for transmission in separate frequencyresources in accordance with a frequency division multiplexing (FDM)technique.

In Example 3, the subject matter of one or any combination of Examples1-2, wherein the processing circuitry may be further configured toencode, for the V2V sidelink transmission by the UE, a short physicalsidelink shared channel (sPSSCH) based on a block of data bits. ThesPSSCH may be encoded for transmission, in accordance with a timedivision multiplexing (TDM) technique, in a short TTI that occurs afterthe selected short TTI.

In Example 4, the subject matter of one or any combination of Examples1-3, wherein the processing circuitry may be further configured toencode the legacy PSCCH for transmission in first frequency resourcesallocated for V2V sidelink transmissions by legacy UEs. The processingcircuitry may be further configured to encode the sPSCCH fortransmission in second frequency resources allocated for V2V sidelinktransmissions by non-legacy UEs.

In Example 5, the subject matter of one or any combination of Examples1-4, wherein the processing circuitry further configured to determineone or more sensing or signal quality measurements for the plurality ofshort TTIs based on one or more channel sense operations prior to thelegacy TTI. The processing circuitry may be further configured to selectthe short TTI for the V2V sidelink transmission by the UE based at leastpartly on the sensing or signal quality measurements.

In Example 6, the subject matter of one or any combination of Examples1-5, wherein the legacy TTI may span one millisecond (msec). Theplurality of short TTIs may include four short TTIs.

In Example 7, the subject matter of one or any combination of Examples1-6, wherein the selected short TTI may span a plurality of symbolperiods. At least one of the symbol periods may be based on demodulationreference signals (DMRS). At least one of the symbol periods may bebased on data bits.

In Example 8, the subject matter of one or any combination of Examples1-7, wherein the processing circuitry may be further configured toencode, for transmission in a first chronological symbol period of thelegacy TTI, an automatic gain control (AGC) element to enable AGC atlegacy UEs in a shared AGC symbol.

In Example 9, the subject matter of one or any combination of Examples1-8, wherein the processing circuitry may be further configured toencode the AGC element for transmission in the first chronologicalsymbol period of the legacy TTI independent of a position of theselected TTI within the legacy TTI.

In Example 10, the subject matter of one or any combination of Examples1-9, wherein the sPSCCH may include a sidelink control information (SCI)that indicates first information related to the V2V sidelinktransmission by the UE. The legacy PSCCH may include a sidelink controlinformation (SCI) format-1 (SCI-F1) indicates second information relatedto the V2V sidelink transmission by the UE.

In Example 11, the subject matter of one or any combination of Examples1-10, wherein the processing circuitry may be further configured to seta duration of a resource selection window according to a latencycriteria, wherein the latency criteria is less than or equal to 20milliseconds.

In Example 12, the subject matter of one or any combination of Examples1-11, wherein the apparatus may further include a transceiver totransmit the legacy PSCCH and the sPSCCH.

In Example 13, the subject matter of one or any combination of Examples1-12, wherein the processing circuitry may include a baseband processorto select the short TTI.

In Example 14, a computer-readable storage medium may store instructionsfor execution by one or more processors to perform operations forcommunication by a User Equipment (UE). The operations may configure theone or more processors to select, from candidate resource pools, aresource pool for a vehicle-to-vehicle (V2V) sidelink transmissions bythe UE. Sub-frames of different candidate resource pools may benon-overlapping. The candidate resource pools may be allocated for V2Vtransmissions of different latencies per candidate resource pool. Theoperations may further configure the one or more processors to, during asensing window before the selected resource pool, attempt to detect V2Vsidelink transmissions by other UEs. The operations may furtherconfigure the one or more processors to determine, based on sidelinkcontrol information (SCI) included in V2V sidelink transmissionsdetected in the sensing window, one or more candidate sub-frames of aresource selection window available for the V2V sidelink transmission bythe UE. The resource selection window may be subsequent to the sensingwindow.

In Example 15, the subject matter of Example 14, wherein the operationsmay further configure the one or more processors to select, from thecandidate sub-frames, one or more sub-frames for the V2V sidelinktransmission by the UE in the resource selection window. The operationsmay further configure the one or more processors to encode, fortransmission in the selected sub-frames, a physical sidelink sharedchannel (PSSCH) based on a block of data bits.

In Example 16, the subject matter of one or any combination of Examples14-15, wherein the operations may further configure the one or moreprocessors to select the one or more sub-frames for V2V sidelinktransmissions by the UE in multiple resource selection windows that areshifted in time.

In Example 17, the subject matter of one or any combination of Examples14-16, wherein the operations may further configure the one or moreprocessors to select the one or more sub-frames to include the candidatesub-frame that is earliest in the resource selection window.

In Example 18, the subject matter of one or any combination of Examples14-17, wherein the candidate resource pools may be configured forsensing windows of different durations. The durations may be based atleast partly on reservation periods of the candidate resource pools.

In Example 19, the subject matter of one or any combination of Examples14-18, wherein the operations may further configure the one or moreprocessors to determine one or more signal quality or sensingmeasurements during the sensing window. The operations may furtherconfigure the one or more processors to determine the candidatesub-frames based at least partly on the signal quality or sensingmeasurements.

In Example 20, the subject matter of one or any combination of Examples14-19, wherein the resource pool may include multiple sub-channels persub-frame. The signal quality or sensing measurements may include achannel busy ratio (CBR) based at least partly on a ratio, for thesub-channels during a window of sub-frames, of: a total number ofsub-channels for which a signal quality measurement is above athreshold, and a total number of sub-channels.

In Example 21, the subject matter of one or any combination of Examples14-20, wherein the operations may further configure the one or moreprocessors to select the resource pool from the candidate resource poolsbased at least partly on: a target latency of the V2V sidelinktransmission by the UE, and the different latencies per candidateresource pool.

In Example 22, the subject matter of one or any combination of Examples14-21, wherein the resource selection window may span a range between: afirst configurable value between zero and four milliseconds (msec), anda second configurable value between the first configurable value and 20msec.

In Example 23, an apparatus of a User Equipment (UE) may comprisememory. The apparatus may further comprise processing circuitry. Theprocessing circuitry may be configured to select, from a plurality ofshort transmission time intervals (TTIs), a short TTI for avehicle-to-vehicle (V2V) sidelink transmission by the UE. A legacy TTImay be divided to include the short TTIs. The processing circuitry maybe further configured to encode, for transmission in accordance with theselected short TTI, a short physical sidelink control channel (sPSCCH)to indicate the V2V sidelink transmission by the IE. The processingcircuitry may be further configured to encode, for transmission inaccordance with the selected short TTI, a short physical sidelink sharedchannel (sPSCCH) based on a block of data bits. The processing circuitrymay be further configured to encode, for transmission in a firstchronological symbol period of the legacy TTI, an automatic gain control(AGC) element to enable AGC at legacy UEs or non-legacy UEs. The memorymay be configured to store information that identifies the short TTI.

In Example 24, the subject matter of Example 23, wherein the short TTIsmay be allocated for V2V sidelink transmissions by non-legacy UEs. Thelegacy TTI may be allocated for V2V sidelink transmissions by legacyUEs.

In Example 25, the subject matter of one or any combination of Examples23-24, wherein the legacy TTI may span one millisecond (msec). Theplurality of short TTIs may include four short TTIs.

In Example 26, the subject matter of one or any combination of Examples23-25, wherein the selected short TTI may span a plurality of symbolperiods. At least one of the symbol periods may be based on demodulationreference signals (DMRS). At least one of the symbol periods may bebased on a block of data bits.

In Example 27, the subject matter of one or any combination of Examples23-26, wherein the processing circuitry may be further configured toencode the AGC element for transmission in the first chronologicalsymbol period of the legacy TTI independent of a position of theselected TTI within the legacy TTI.

In Example 28, an apparatus of a User Equipment (UE) may comprise meansfor selecting, from candidate resource pools, a resource pool for avehicle-to-vehicle (V2V) sidelink transmissions by the UE. Sub-frames ofdifferent candidate resource pools may be non-overlapping. The candidateresource pools may be allocated for V2V transmissions of differentlatencies per candidate resource pool. The apparatus may furthercomprise means for, during a sensing window before the selected resourcepool, attempting to detect V2V sidelink transmissions by other UEs. Theapparatus may further comprise means for determining, based on sidelinkcontrol information (SCI) included in V2V sidelink transmissionsdetected in the sensing window, one or more candidate sub-frames of aresource selection window available for the V2V sidelink transmission bythe UE. The resource selection window may be subsequent to the sensingwindow.

In Example 29, the subject matter of Example 28, wherein the apparatusmay further comprise means for selecting, from the candidate sub-frames,one or more sub-frames for the V2V sidelink transmission by the UE inthe resource selection window. The apparatus may further comprise meansfor encoding, for transmission in the selected sub-frames, a physicalsidelink shared channel (PSSCH) based on a block of data bits.

In Example 30, the subject matter of one or any combination of Examples28-29, wherein the apparatus may further comprise means for selectingthe one or more sub-frames for V2V sidelink transmissions by the UE inmultiple resource selection windows that are shifted in time.

In Example 31, the subject matter of one or any combination of Examples28-30, wherein the apparatus may further comprise means for selectingthe one or more sub-frames to include the candidate sub-frame that isearliest in the resource selection window.

In Example 32, the subject matter of one or any combination of Examples28-31, wherein the candidate resource pools may be configured forsensing windows of different durations. The durations may be based atleast partly on reservation periods of the candidate resource pools.

In Example 33, the subject matter of one or any combination of Examples28-32, wherein the apparatus may further comprise means for determiningone or more signal quality or sensing measurements during the sensingwindow. The apparatus may further comprise means for determining thecandidate sub-frames based at least partly on the signal quality orsensing measurements.

In Example 34, the subject matter of one or any combination of Examples28-33, wherein the resource pool may include multiple sub-channels persub-frame. The signal quality or sensing measurements may include achannel busy ratio (CBR) based at least partly on a ratio, for thesub-channels during a window of sub-frames, of: a total number ofsub-channels for which a signal quality measurement is above athreshold, and a total number of sub-channels.

In Example 35, the subject matter of one or any combination of Examples28-34, wherein the apparatus may further comprise means for selectingthe resource pool from the candidate resource pools based at leastpartly on, a target latency of the V2V sidelink transmission by the UE,and the different latencies per candidate resource pool.

In Example 36, the subject matter of one or any combination of Examples28-35, wherein the resource selection window may span a range between: afirst configurable value between zero and four milliseconds (msec), anda second configurable value between the first configurable value and 20msec.

The Abstract is provided to comply with 37 C.F.R. Section 1.72(b)requiring an abstract that will allow the reader to ascertain the natureand gist of the technical disclosure. It is submitted with theunderstanding that it will not be used to limit or interpret the scopeor meaning of the claims. The following claims are hereby incorporatedinto the detailed description, with each claim standing on its own as aseparate embodiment.

1.-27. (canceled)
 28. A user equipment (UE), comprising: memory; and processing circuitry in communication with the memory and configured to: select a sidelink resource for sidelink transmission; and transmit the sidelink transmission on the selected sidelink resource, wherein the sidelink transmission includes an initial orthogonal frequency division multiplexing (OFDM) symbol, wherein the initial OFDM symbol is a copy of a second OFDM symbol, wherein the second OFDM immediately follows the initial OFDM symbol, and wherein the second OFDM symbol includes at least one of a physical sidelink shared data channel or a physical sidelink control channel.
 29. The UE of claim 28, wherein, when the sidelink transmission includes 6 symbols, a second symbol and a sixth symbol of the sidelink transmission are demodulation reference signals (DM-RS).
 30. The UE of claim 28, wherein, when the sidelink transmission includes 7 symbols, a second symbol and a sixth symbol of the sidelink transmission are demodulation reference signals (DM-RS).
 31. The UE of claim 28, wherein the processing circuitry is further configured to: reserve a first set of resources for the sidelink transmission; and reserve a second set of resources for a second transmission process, wherein the first set of resources and the second set of resources are shifted in time with respect to one another.
 32. The UE of claim 28, wherein the processing circuitry is further configured to: transmit information for reservation for resources for the sidelink transmission to a second UE.
 33. The UE of claim 32, wherein the information for the reservation of resources for the sidelink transmission to the second UE further includes resources for an acknowledgment to be received from the second UE.
 34. The UE of claim 28, wherein the processing circuitry is further configured to: sense resources during a sensing window.
 35. A method for transmitting a sidelink transmission, comprising: a user equipment, selecting a sidelink resource for sidelink transmission; and transmitting the sidelink transmission on the selected sidelink resource, wherein the sidelink transmission includes an initial orthogonal frequency division multiplexing (OFDM) symbol, wherein the initial OFDM symbol is a copy of a second OFDM symbol, wherein the second OFDM immediately follows the initial OFDM symbol, and wherein the second OFDM symbol includes at least one of a physical sidelink shared data channel or a physical sidelink control channel.
 36. The method of claim 35, wherein, when the sidelink transmission includes 6 symbols, a second symbol and a sixth symbol of the sidelink transmission are demodulation reference signals (DM-RS).
 37. The method of claim 35, wherein, when the sidelink transmission includes 7 symbols, a second symbol and a sixth symbol of the sidelink transmission are demodulation reference signals (DM-RS).
 38. The method of claim 35, further comprising: the UE, reserving a first set of resources for the sidelink transmission; and reserving a second set of resources for a second transmission process, wherein the first set of resources and the second set of resources are shifted in time with respect to one another.
 39. The method of claim 35, further comprising: the UE, transmitting information for reservation for resources for the sidelink transmission to a second UE.
 40. The method of claim 39, wherein the information for the reservation of resources for the sidelink transmission to the second UE further includes resources for an acknowledgment to be received from the second UE.
 41. The method of claim 35, further comprising: the UE, sensing resources during a sensing window.
 42. A non-transitory computer-readable storage medium that stores instructions for execution by one or more processors to perform operations for communication by a user equipment (UE), the operations to configure the one or more processors to: select a sidelink resource for sidelink transmission; and transmit the sidelink transmission on the selected sidelink resource, wherein the sidelink transmission includes an initial orthogonal frequency division multiplexing (OFDM) symbol, wherein the initial OFDM symbol is a copy of a second OFDM symbol, wherein the second OFDM immediately follows the initial OFDM symbol, and wherein the second OFDM symbol includes at least one of a physical sidelink shared data channel or a physical sidelink control channel.
 43. The non-transitory computer-readable storage medium of claim 42, wherein, when the sidelink transmission includes 6 symbols, a second symbol and a sixth symbol of the sidelink transmission are demodulation reference signals (DM-RS).
 44. The non-transitory computer-readable storage medium of claim 42, wherein, when the sidelink transmission includes 7 symbols, a second symbol and a sixth symbol of the sidelink transmission are demodulation reference signals (DM-RS).
 45. The non-transitory computer-readable storage medium of claim 42, wherein the operations further configure the one or more processors to: reserve a first set of resources for the sidelink transmission; and reserve a second set of resources for a second transmission process, wherein the first set of resources and the second set of resources are shifted in time with respect to one another.
 46. The non-transitory computer-readable storage medium of claim 42, wherein the operations further configure the one or more processors to: transmit information for reservation for resources for the sidelink transmission to a second UE, wherein the information for the reservation of resources for the sidelink transmission to the second UE further includes resources for an acknowledgment to be received from the second UE.
 47. The non-transitory computer-readable storage medium of claim 42, wherein the operations further configure the one or more processors to: sense resources during a sensing window. 